The decision to research and consider a British atomic bomb was taken by a small inner circle of ministers, and in early 1946 Clement Attlee, the British Prime Minister, personally persuaded the semiretired Viscount Portal of Hungerford to take the post of Controller of Production, Atomic Energy, and to assemble an appropriate team. Portal duly set up his headquarters in central London within the Ministry of Supply’s Atomic Energy Directorate, in a wired-in enclosure on the fourth floor of Shell-Mex House. Ironically, this dour building in the Strand stood on a site owned long before by the politically powerful Salisbury dynasty! From there Portal recruited his senior personnel. These included Wing Commander (later Air Vice-Marshal) John ‘Archie’ Rowlands, who would be closely involved with the ballistic design of the weapon, and William Penney, who knew more than any other British scientist about the methods used to develop the American bomb.
Uncharacteristically for a scientist, William Penney had a talent for devising brilliantly innovative administrative structures. An opportunity to put that into effect occurred as a consequence of an inner-circle Cabinet meeting on 8 January 1947 at which the momentous decision was taken to proceed with the building of a British atomic bomb which could be test-exploded before summer 1952. The select few ministers present endorsed a memo sent by Portal, but based on Penney’s ideas, describing how secrecy might best be maintained during this crucial development stage.6 The recommendation accepted was that rather than building an atomic weapon through the ordinary agencies in the Ministry of Supply it should be developed under special arrangements conducive to the utmost secrecy. Penney’s brilliant idea was that the facilities for the necessary research and development could be ‘camouflaged’ as Basic High Explosive Research – a subject for which he was actually responsible but on which no work was being done. It was agreed that just as had been done at Shell-Mex House, at Fort Halstead and Woolwich Arsenal special fenced-off enclaves should be formed within the main establishment.
The camouflage concept meant basing the work on a section within the Armaments Research Establishment, to form a cell there and subcontract bits of work to other parts of the government machine. To coordinate this subcontracted atomic bomb work, in November 1948 the High Explosives Research Operational Distribution Committee (HEROD) was established. Although in almost all respects the farming-out practice was ideal, even for the ballistics elements, there were a couple of components – the fusing system and radioactive parts of the bomb – which Penney’s High Explosive Research (HER) boffins at Fort Halstead would need to do themselves. This decision necessitated taking on many more staff, and resulted in a move in early 1950 to a disused airfield site at Aldermaston in Berkshire, which subsequently became the Atomic Weapons Research Establishment (AWRE). No wonder Heligoland’s links with the development of the atomic bomb remained hidden for so long.
No nuclear bomb was ever actually exploded on Heligoland, although it is quite probable that such a fate might have been contemplated for the island, however fleetingly. It appears that in five distinct respects – seismic measuring, blast effect, ballistic shape, crew training and USAF involvement – the island was used in the development of techniques, and in the collection of data required for the eventual testing of an atomic bomb elsewhere in the world.
‘The greatest non-atomic explosion in history’ was how The Times described the ‘Big Bang’ which occurred on 18 April 1947. There was an eerie sense of persecution about the entire operation. It happened at noon, precisely two years after the island’s failure to surrender led to its initial devastation in an enormous RAF raid. And now the Royal Navy seemed ready to finish it off. Safely aboard HMS Lassco, anchored 9 miles offshore, the moment the fourth pip in the BBC’s time signal sounded Frank Woosnam pressed a firing button and detonated the 7,000 tons of munitions in the island’s labyrinth of deep tunnels.
According to the Daily Express, ‘From the island’s centre, like a Bikini mushroom, rose a massing cauliflower of smoke as the blast from the deepest tunnels of the fortress 180 feet down in the rock surged to the surface.’ The New York Times said ‘the island seemed to rise out of the sea in a spectacular red and black explosive flame. In seconds, the cloud was twice the size of the island. As these layers moved off, one could see and feel the articles of red sandstone that gave the cloud its reddish tint.’ Reporting an eyewitness from an observation plane describing the island as seeming to ‘take off into the air’, the Associated Press also claimed the blast was ‘the biggest man-made explosion since the American Navy’s atom bomb tests at Bikini’. The explosion had sent the tall Monk rock, one of the sandstone pillars carved by the seas, crashing into the waves. But when the 8,000ft column of smoke cleared it was evident that only about 14 per cent of the island’s surface had fallen into the sea. All the rest stood firm, enhancing Heligoland’s reputation for defiance.
According to the New York Times British newscasters to Germany were reported to have been ‘asked to play down’ coverage of the Big Bang. But some intriguing accounts did slip out, such as the Daily Telegraph’s showing that inexplicably, on an RAF Mosquito and a destroyer, HMS Dunkirk, there had been microphones to record the explosion.7 Declassified confidential guest lists done at the time, of the numerous VIPs invited to witness the event from a safe distance on Royal Navy ships, make rather curious reading because they now appear to have noticeably refrained from mentioning the names of any important scientists there. Yet stories which appeared in the New York Times on 18 and 19 April 1947 stated that there were present senior American boffins from the acoustics department of the United States Naval Ordinance Laboratories. That ten-strong delegation had been headed by Dr John Atanasoff and Commander Beauregard Perkins who had also – the newspaper revealed – ‘observed the Bikini explosions’. Important though they were, the absence of any mention in British official records indicates that the British government was being careful not to draw attention to them. Yet, unexpectedly, a glimmer of their presence accidentally did slip out. On 18 April 1947 the Daily Telegraph happened to report that on the morning prior to the Big Bang the destroyer Nepal had arrived from the Forth and anchored off Heligoland. Intriguingly the article also noted the ship had brought ‘a party of scientists. They have a seismograph and other apparatus with which to record the effects of the explosion.’ Seemingly arriving among that party of scientists were members of William Penney’s team. According to US Naval Intelligence records of Commonwealth warships the Nepal certainly existed then – it was a Royal Australian Navy destroyer stationed in British waters. That is why the Public Record Office has no incriminatory ship’s log of such a Royal Navy vessel at that time.
The explosion was so powerful that it registered on over a hundred seismographs in seismic stations in various parts of Europe – notably in Germany, France and Britain (at Kew). However, what use was that to Penney’s boffins at the HER if they could not be sure exactly what quantity of explosives produced such shock waves? The Hiroshima bomb had been equal to 12,500 tons of TNT – a yield of 12.5 kilotons. It was envisaged that the Heligoland ‘Big Bang’ explosion would be more than half of that at 7 kilotons – but it was not.
The event had long been stated by the Admiralty as being ‘the greatest demolition operation ever performed by the Royal Navy’, and officially their declared view of ‘Big Bang’ was that it had been ‘A 100% successful operation’. They even publicly announced that all members of the demolition team would be recommended for decorations. In reality, to the consternation of senior naval officers, a significant proportion of the explosives had failed to go off. This was 62 tons of the mysteriously late-arrival TNT which had stubbornly refused to explode on the Heligoland quayside. Instructed to return to the island without publicity (including radio silence) and finish the job, Woosnam’s team secretly arrived there on 22 April 1947 in an R-boat and a captured German submarine. Fresh cordex-linked charges having been laid, firing wires were led to the Red Tower. The ML 150 and the U-boat having been put to sea to ensu
re there were no other craft in the vicinity, that night Woosnam set off the detonation.
That so-called ‘Little Bang’ took the form of a bright flash, and because the cloud cover was low, the loud detonation report even rattled doors and windows in Cuxhaven.8 Woosnam’s superiors, who had wanted the ‘Little Bang’ explosion to be discreet, were again furious. Uninformed by him, because of the radio silence, as to when the explosion would take place, they despatched a British destroyer from Cuxhaven to investigate the bright flash. Unusually, in the absence of any official account, these events were chronicled in a file Woosnam himself deposited in the Public Record Office in March 1950. And so the story remained hidden until January 1980, when – still not having received his medal – Woosnam found an Admiralty note in the newly opened PRO file accusing him of having made ‘an error of judgement’. Indignant at being so besmirched he privately deposited a fuller chronicle, which significantly noted there had been no reprimand for any officer for the, still unexplained, despatch of the superfluous TNT to Heligoland.
The rest of the world must have assumed that once the almighty ‘Big Bang’ had been carried out there could be no need for further static explosions on the island. In fact during the summer of 1947 Penney’s HER’s interest in extracting seismic data from Heligoland became more focused. Released official papers show that on 30 May 1946 a special meeting was held at the Ministry of Works. In response to ‘the advent of the atomic bomb’, an urgent need was expressed by Sir Geoffrey Taylor, the Chairman of the Civil Defence Research Committee, to obtain seismic records by which to have a better knowledge of the propagation of blast in air-raid tunnels and other confined spaces. Taylor, a British scientist earlier assigned to the Manhattan Project, had made a name for himself as an expert in blast waves caused by high explosives. Penney was present at that meeting whose minutes show that, in terms of tunnels to be used for test explosions supervised by the Directorate of Armament Research, ‘It was agreed that the most suitable tunnels were those on Heligoland’. Inexplicably that Civil Defence Committee gathering had before it a memo by their Chief Defence Advisers hypothetically noting that: ‘If an atomic bomb equivalent to 20,000 tons of TNT were exploded 100 feet below ground there would result a crater estimated to contain, initially, about ten million tons of soil.’9 Then on 22 April 1947, just three days after the ‘Big Bang’ the Committee – still including Penney – met again, this time at the Ministry of Supply, and agreed that ‘part of the tunnel system at Heligoland should be used’ in specialist trial explosions to determine the effect of shock waves.
The person selected to obtain readings was Major F. Taggart of the innocuous-sounding ‘Explosive Storage and Transport Committee’, based at Woolwich in an enclave codenamed B43. Contrary to press claims, not quite all of Heligoland’s tunnels had been blown up in April 1947. One area remained: the only civilian air-raid shelter, known as the Spirale. Situated in the centre of the eastern side of the rock, it was a deep double spiral tunnel which led up to the surface of the Oberland. The tunnels were fitted with three tiers of bunks all the way up, and there the whole civilian population used to shelter when the island was bombed. A now declassified (but hitherto unopened) Foreign Office document (FO 371, German General Economic, 1947) reveals that on 5 November 1947 Taggart wrote a letter in which he clearly stated that it was desirous ‘to obtain detailed information about the area covered by a radius of 200 yards from the Spirale which is adjacent to the north-east harbour’. He then went on to request a large-scale map, ‘25 inches to the mile at least’.
During the summer of 1947 the Explosive Storage and Transport Committee (which seems to have been an integral part of Penney’s HER) became determined to keep this new seismic data from other scientists. The ‘Big Bang’ on 18 April had been a fairly high-profile event, and the Royal Society had been allowed to take its own seismic observations (as they had at some other large demolitions at Soltan on the German mainland). Their agent, in that respect, which had obtained permission for them, was the Department of Geodesy and Geophysics at the University of Cambridge. That department’s Dr Edward Bullard had also attended the April ‘Big Bang’. Having heard that Major Taggart was intending to conduct some unusual experiments on Heligoland in early September 1947, both the Royal Society and Dr Bullard wrote to the Foreign Office in London to ask them to forward their request to attend that autumn’s test explosion. The letter of recommendation, dated 14 August 1947, from the Foreign Office’s London headquarters to the German Section, is particularly illuminating because it revealed for the first time that German experts under Allied protection were cooperating in these test activities in Heligoland.10 It stated: ‘You will remember that valuable scientific observations were made on Heligoland early this year by British scientists from the Royal Society, with the cooperation of Research Branch CCG and German experts.’ With regard to the demolitions which it understood were due to take place in September 1947 it said that the Royal Society again wished to be present to undertake extensive seismological observations of its own: ‘We presume the Research Branch will make the necessary arrangements as before. Please ensure that the British and German scientists engaged in this operation receive all the facilities necessary to make that a success.’
However, in sharp contrast to their cooperativeness earlier in the year, the Research Branch were now utterly unwilling to encourage witnesses to the unusual explosions that Major Taggart was preparing to conduct. In a rather disgruntled letter of 29 August 1947, responding to the Foreign Office request, it refused to cooperate, claiming that such visitors could not be allowed because there was an acute shortage of rations! The author of this letter was clearly harassed, and in the course of his annoyed ramblings let slip that the department already had enough to do with other ‘Matchbox’ projects on which German boffins were employed. These were technicians who were brought over to the British side immediately after the end of the war. Some of them were atomic scientists who became involved in Britain’s own atomic bomb-making project.
Sir Geoffrey Taylor, chairman of the Civil Defence Research Committee, had been influential in another respect. It was he who, having realised how invaluable was Penney’s special knowledge of the behaviour of shock waves, earlier recommended he be appointed Chief Superintendent of Armament Research; and so, in effect, the head of Britain’s A-bomb programme. Penney was fascinated by a phenomenon called ‘base surge’ which he had witnessed at Bikini Atoll. In an Atomic Weapons Research Establishment report, written in January 1948, he defined it as: ‘When a column of spray and mist is thrown into the air by an underwater explosion it subsequently collapses under gravity and spreads over the water surface, giving a so-called Base Surge.’11 In the early years of Britain’s A-bomb research development Penney envisaged the most likely targets for such a weapon in wartime as being estuaries and harbours full of enemy shipping. With that in mind on 19 May 1948 he had written to Vice-Admiral Daniel, the Controller of the Navy: ‘Recently I have been trying to work out the minimum depth of water which will give a base surge for an atomic bomb of present design.’ Describing the need for the research, he had admitted in his January report: ‘It is of importance to know the laws governing the collapse and spread of the column, and for this reason Trial Charybdis was devised.’
A released Foreign Office paper, FO 371, indicates that Heligoland’s Dune isle was the first choice of site for the experiment. On 13 August 1947 it stated that ‘Major Taggart is conducting experiments on Dune in September of this year’. That was confirmed in a September 1947 Atomic Weapons Research Establishment report of the ‘Charybdis’ trial, the stated purpose of which was to monitor the outward movement of a falling vertical column of water which had been ‘formed by atomisation’. This AWRE report, now available, clearly states: ‘It was considered that the trial might be carried out with surplus naval depth charges and the possibility was examined of carrying one or more experiments on the 20,000lb scale near the island of Heligoland during the progr
ess of other trials for the Explosive Storage and Transport Committee.’ But instead, for undisclosed reasons, it was decided to do the test detonation in shallow waters 1,800 yards off Foulness Island on the northern edge of the Thames estuary. The apparatus used in the first Charybdis detonation consisted of conventional naval torpex depth charges together with cordex fuse-wire (for instantaneous detonation), elements of which – other than the precise hexagonal lattice pattern in which they were closely packed – were most similar to those used by Woosnam on Heligoland just a few months earlier. The first such test explosion occurred at Foulness on 3 October 1947.
Although notionally just an ‘enclave’ within the Army’s Shoeburyness range, as early as November 1945 the Foulness range adjacent to that had been prepared for Penney’s HER team to use for experimental work on bombs and shells. By 1947 Foulness was effectively an AWRE range with its own blast measurement group. In 1950 actual radiation explosions were being carried out there. On 2 May of that year the Superintendent of Armament Research at Foulness wrote a letter to the Admiralty’s Director of Physical Research, claiming ‘we would be happy to agree’ to it being used for the Admiralty’s ‘next series of radiation measurement experiments’. Heligoland seems to have be lucky, insofar as it was never used for actual radiation tests.
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