‘Who knows?’ I began. ‘There may be micro-sites down there. Corners where something’s survived.’
‘Does it sound,’ the voice went on, ‘like something you’d be able to do?’
‘Well, I can try, but I have to warn you that I might not find anything.’ I went on to describe the potential problem with farmed soils.
The thought of a dead body did not much bother me. I could vividly remember having my arms full with a cloth-wrapped dismembered leg as I walked down the corridor of Charing Cross Hospital. It was destined for an infusion experiment in the research laboratory. A body is just a body. It is flesh, blood, and bone. No, what bothered me was that this was the great unknown. Police work was a different world, and not one I had ever thought to visit. I had no idea about forensic protocols; I had never heard the term ‘trace evidence’, nor any of the other terms, acronyms, and phrases I would soon discover. I had, in my day-to-day life, become practised at imagining the landscapes of the past – but to contemplate the landscapes of the present, to search for something that had been left behind, to invent procedures where none had been invented before? As I listened to the detective’s breathing on the other end of the line, all of that seemed an entirely new frontier. This was a bit like Star Trek – ‘To boldly go!’.
Then I thought: you keep asking yourself why but why not? You’ve done it before. You’ve worked in laboratories and hospitals, reinvented yourself as a high-flying secretary in the building industry, reinvented yourself again as a microbiologist, and yet again as a palynologist. And isn’t that part of science? To be curious and try? You never planned your life before. Why not embrace the opportunity now?
If it did not work, it did not work. Nothing ventured meant nothing gained – but it would not matter to me. There was always my work in archaeology which I really enjoyed. There were always features from the past, waiting to be excavated and rediscovered. So, for the rest of the day, I thought very little about the murdered man and Bill’s Glaswegian voice on the other end of the line. It sounded like an interesting exercise, but really, that was all. How was I to know it would dictate the direction of the second half of my life?
The car used for dumping the victim in the field ditch was waiting in the police garage, looking just like any other old car. Its wheel arches were spattered with dirt; there was general grime along the bottoms of the doors, with a few superficial soil smears. The police garage attendant who led me in, flicking on the overhead lights to illuminate the waiting vehicle, did not look particularly impressed. ‘I don’t know what they brought you down for,’ he said, barely concealing his scorn. I eventually came to expect this kind of dismissive sarcasm in the early years. ‘There’ll be pollen all over the thing. That car’s been up and down and all over. Just look at the state of it …’
I crouched down on one side of the car, and then on the other. The outside of the car looked as if it ought to have been a bounty of information – but how to extract it, and where to begin, I had absolutely no idea.
I had already asked the police to get me samples of surface soil from the field where the body had been found – from the wheel tracks. I had put it through the usual process but, as expected, the microscope revealed only an occasional speck of residual cellulose, stained bright red by my safranine dye. The rest was what I called background ‘grot’, with an occasional fragment of a pollen grain, decayed beyond recognition. My prediction of thorough decomposition of organic remains in that soil was correct. Looking at the soil traces in the treads of the tyres, the accumulated tidemarks of black, silty deposits in the wheel arches – and, inside, the vague dusty footprints on the floor mats – I wondered if I would find anything at all. But the garage attendant was squinting at me, expecting me to find nothing, and this galvanised me more than ever. It was impossible to do anything under those conditions, and I was pretty fed up with the officer’s attitude, so I chose those parts of the vehicle I thought might be most productive and instructed the officers to send them to our laboratory.
So much has been on a steep learning curve. The chassis elements of vehicles vary greatly, but I now know the most likely nooks and crannies that might collect relevant evidence. Back then I knew nothing – I had never even seen the underneath of any motorised vehicle, certainly not at first hand with my face about five centimetres from the oily, grimy metal of the various pipes and struts. I soon came to realise that I would just have to do my best and, by trial and error, find the most efficient way to sample these things. I was used to scrubbing the dirt from various artefacts to find out what they had contained. Could this be so dissimilar? So, I just used my common sense; I started with the most easily removed items and asked that they be brought to me – footwell mats, pedals, bumper, air filters, and radiator. Initially, I ignored the wheels because they could have picked up material from a multitude of places. On the other hand, the inside of the car would contain mostly material that was transferred to it from people’s feet, and the objects they carried in it. Simple logic guided me and, in any case, if I were wrong, the rest of the car would still be in the garage and could be resampled.
I was glad to get away from the sarcastic and downright rude police garage attendant. It took me an age to scrub and wash the various items meticulously, and to sieve and decant the silty washings so that they could be centrifuged down to concentrated pellets. The worst item was the radiator, which yielded great clumps of insects. I saved these and asked a colleague to have a look at them but I did the rest.
There was pollen everywhere. The attendant who poured such scorn on the endeavour had been right about one thing: the body of the car was a veritable botanic garden of different pollen types, and they had obviously come from different sources. I subjected the centrifuged pellets to standard processing just as if they were archaeological samples. This involved using a sequence of very strong and noxious acids to remove the background matrix of the soil – the quartz (sand), clay, cellulose, lignin, and humic acids. In the best possible scenario, only the various palynomorphs would remain.
As amazing as it sounds, the outer coats of such palynomorphs, pollen grains, spores, fungal remains, insects, and crustaceans, all contain incredibly resistant polymers that can withstand the vicious treatments involved in the methods. These polymers are sporopollenin in the case of plants, and chitin in the case of fungi and animals. The method is so dangerous that one must never be left alone in the laboratory when engaged in this work, and layers of protective clothing, gloves and a mask must be worn. No one is allowed to enter the room when the processing is in progress, and every precaution is made to eliminate contamination by stray, airborne pollen grains. Slide traps are also placed around the laboratory, on windowsills, on the surface in the fume cupboard, and randomly elsewhere. In this way, it is possible to check for contaminants floating around in the air. I also ran blanks to test the various reagents to make sure that they were not contaminated in any way.
Once the background matrix of the soil had been removed, the pollen, spores, and other organic remnants that had miraculously survived were stained and embedded in jelly. The jelly from each sample was then spread thinly on a glass slide and allowed to set. Only now could the really hard work begin. I had never examined objects such as vehicles, clothing, footwear, or anything else so modern and mundane. But I was enthralled. Every sample from the car contained abundant pollen, spores, and fragments of insects, as well as microscopic entities that eluded immediate identification.
The radiator mesh at the front of the car had drawn in everything to which the car had been exposed. Here was a hotchpotch of remains of organism that indicated the rural and the urban, of farmland, and woodland. Who knew how long it had coated the inside of the mesh? The tyres, too, were so palyniferous that they certainly represented more than one place – probably hundreds of places – so too the chassis, where shreds of material, bits of plant, clods of earth and puddle water had all left their impression. I had managed to extract a rich mosaic of
microscopic matter that was diverse and well preserved, yet proved exactly … nothing. The total information was rich and bountiful but so muddled that it was worthless. Yet, as the work progressed slowly, I realised that some parts of the car were giving more specific results. The tyre treads themselves had picked up dirt from everywhere the car had been driven – but the inside wall of the tyre represented more singular landscapes, with much less pollen finding its way into these hidden corners. I began to see that different parts of the car accumulated different material. The differences were not large, but we work in a microscopic world. Small differences matter. One thing that was very noticeable was the unexpected dominance of tree pollen in samples from the outside body of the vehicle.
Then I started investigating the insides of the car, enjoying myself as I began hitting my stride – and everything changed.
I had not been expecting it – but then, I had so little idea just what to expect. The inside of the car was much cleaner and free of grime, at least the kind of dirt visible to the naked eye. I analysed the fabric from the seats, the air filters, the window frames, every nook and cranny inside that car, and the results were just not interesting at all, but what leapt out at me was that the profile of the foot pedals, and the mats beneath them, matched. It was not a perfect match. Nothing ever is in this kind of study. But their profiles both reflected the same kind of place. They both had pollen of dogwood, dog rose, oak, hawthorn, bramble, field maple, ivy – and lots of Prunus-type pollen. Looking at the rest of the assemblage making up this plant community, I was certain that the Prunus-type was blackthorn, the very common plant that generously gives us its little plum-like fruit which makes lovely sloe gin. What interested me, too, was the preponderance of pollen from weeds normally found at the edges of arable fields. In archaeological contexts they are regarded as indicators of past crop-growing – black nightshade, poppy, white dead-nettle, stinging nettle, woundwort, docks, goosefoot, and grasses, to name a few. I also found some cereal pollen. Of course, cereals are grasses and their pollen grains are very similar to each other except for size. These grains were obviously not any of any grass because they were too big; they were not maize because they were far too small; and they were definitely not rye, because they were round rather than a tapering, rounded oblong shape. They were probably of wheat or barley.
A picture of this place was beginning to form in my head. I had been told that the car had driven into a field that was used for growing maize. I did not find any maize pollen, but then I had not really expected it. The way that field soil had been enriched and aerated would have promoted its disappearance by the late winter or early spring. Such treatment would enhance the activity of decomposer microbes, and pollen would just disappear. But the soils at the edges of the field would not have received regular doses of fertilisers and pesticides, or been aerated by ploughing. Importantly, all this meant that microbial activity would be much reduced, and pollen and spores might be better preserved. Importantly, with such a profuse growth of herbs, anyone approaching the ditch could not have failed to step on them. These would deposit their own pollen on shoes, and that of the shrubs and trees of the hedge, as well as being brought by the air from further afield. Even pollen and spores from previous years could remain impacted on leaves and stems, and be present in the ditch itself.
Going through samples and recording your findings is a painstaking, tedious business, but moments like this – when an image slowly forms in front of your eyes – gives great reward. This was an assemblage of pollen I had seen many times before. In fact, it was a typical archaeological assemblage, the kind that has been in Britain for many thousands of years since the first farmers started cultivating crops, and field margins developed.
There was no maize in that field, nor its pollen, but I was looking at the vegetation that had been growing around the crop in previous years, and probably would for many to come. This was evidence that the occupants of that vehicle had stepped on the vegetation growing at the edge of an arable field, that was bordered by a species-rich hedge. The number of tree and shrub pollen types I found probably meant that it was an ancient hedge, and most likely it would have been growing on a bank thrown up by the digging of a ditch in the distant past. To all intents and purposes, we were looking at an archaeological feature. It was coming together.
I picked up the telephone.
The sun was slanting through the Hertfordshire trees as the detective’s car came to a halt, and I clambered out of the back seat. I had jumped at the chance to come out here and see it for myself and here was the hedgerow, stretching far along the edge of the field. There, on the other side of the road, at least 200m away, was a field planted with wheat – that probably explained the cereal pollen I had found although I was rather surprised that it had travelled as far as it had. Experiments by some had shown that it travels only a matter of a few metres from a crop edge – so here was another anomaly in the standard literature.
Field margins up against hedges may be wasted to the farmer but not to wildlife. They are teeming habitats. They are the homes for hundreds of different species: plants, insects, birds, and other animals. And the one whose brambles, nettles, and herb-rich bank stretched away from me now was the place where a man had been dumped and set alight – in the hope that his body would never be found.
The hedge was of various heights, depending on the shrubs growing within it. What a bountiful place it was with so many different species, each producing its specific pollen, leaving traces on whomever touched them. What a contrast to the sterile, bare soil of the field. If there had been a field of maize when the vehicle drove into it, the evidence would have been so easy to interpret. Yes, the field held maize and yes, the vehicle and its occupants would have been swamped with its pollen. Getting evidence like that is very rare though, and this was certainly not the case here. A place as rich and varied as this left so many more markers but, if I had not analysed so many ancient arable field ditches, I might not have put two and two together and realised its significance.
I have thought about hedgerows a lot in my life. In archaeology we might find a certain assemblage of pollen grains indicating a hedgerow and interpret the results to tell the archaeologist that the land had been farmed here in times past – and in that way begin building up an image of how our landscapes might once have been. Now that I stood here, another thought leapt out. What made one part of this hedgerow different from the next? There are hedgerows in Britain several millennia old. Our oldest hedgerows hark back thousands of years, past the Iron Age Celts, past the Dark Ages that took hold after the Romans had left, past early kings and queens, and on, and on into our own history. Hedges develop in various ways but some ancient ones are the vestiges of the forests our Bronze Age ancestors fought back as they claimed the land for farming. And they exist now, often with their ditches and banks, forming barriers between tracts of land, possibly denoting ownerships or boundaries. In the distant past, the boundaries may have been markers between tribal territories; many are now neglected remnants of what they were, but they are still evident.
I could see field maple in the distance, but only hawthorn and oak nearby. In palaeoecology (the study of ecology of the past) and archaeology you dig down and, as you dig deeper, you go back in time. You count the surviving pollen grains, work them out as a proportion of the vegetation and watch, as the ages passed, how birch trees dominated a landscape and then declined to give way over time to pine, then alder, elm, and lime – how they were progressively removed by people and were replaced by grasses and herbs and, in the uplands, the heathers of moorland. In archaeology, you work out the fate of various plants through time, but all those plant communities get conflated through compression of the sediments in your sampling corer, and small differences become compacted together. But here in this field was a single snapshot in time. The difference between this and studies in archaeology, or palaeoecology, was that changes over long periods of time were irrelevant. The most important t
hing was what was here when the body was dumped. Analysis in archaeology is essentially in three dimensions because time is involved, and time is represented by depth of sediment. Here, the analysis is in two dimensions, length and breadth. I did not have to worry about changes over time at all.
I had another flash of inspiration. Although there was so much oak here at the field gate, why did I get only small amounts of its pollen in the samples? And why had I found so much blackthorn-type, along with black nightshade and dead-nettle? There was none here by the gate. This was not just one hedgerow, but many smaller ones, each stretch distinct from the next, and yet merging with it. It may seem blindingly obvious now, but it was not so clear then. No one really understood how the pattern of pollen fallout varied in this kind of scenario.
I was still gazing along the hedgerow, when the scenes-of-crime officer asked, ‘Do you want to see where they put the body?’
‘Well, actually, I’d like to try and find it myself.’
In procession, we walked along the hedgerow, but nothing matched the picture in my head yet. I had to keep in mind both the woody and the herbaceous plants that would have been picked up by the offenders. The hedgerow was wrong, wrong, wrong – and then, suddenly, it was right.
‘I bet this is the place.’
The detectives looked at me. The Deputy Chief Constable’s face widened into a smile. ‘How did you work that out, Pat?’
‘Because I have already seen it … and all in my mind’s eye.’ I had seen the blackthorn and the field maple, their canopies intertwining, and a hawthorn, with the flowering form of ivy insidiously over-topping its upper branches. Grasses, white dead-nettle, black nightshade, woundwort, docks, goosefoot and some nettle all contributed to the dense bank between the bare soil of the field and the ditch itself. These had all shed their pollen onto the leaves of the grassy, herb-rich bank. The offenders had trodden in it and carried it back to their car. That hedge and bank had witnessed them setting his body alight and making their getaway. It was informing on them now.
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