Emergency calls went out to Aldermaston and RAF Wittering. In the gathering gloom, a detachment of men was deployed to try to clear the snow, but two hours later the convoy was still stuck fast. A decision was taken to wait until morning before attempting to get it moving again. Meanwhile rations and blankets were sent out to the men who had been ordered to stay with the vehicles. A group of armed airmen arrived to help guard the convoy.
Some time later a clutch of scientists and technicians sent from Aldermaston approached the stricken Foden and peeled back the heavy folds of the tarpaulin covering. In the harsh glare of hastily erected arc lights, the darkly glistening metallic casing of the huge bomb was revealed. It was 24-feet in length, five in diameter and weighed 8,000 lbs. It appeared to be undamaged, which must have been a considerable relief to the scientists and the War Office, not to mention their political masters in Whitehall.
Grapple Y was more impressive than Grapple X. It was another ‘layer-cake’ device with an atomic trigger, but with less uranium-235 and considerably more lithium-7 deuteride. Various other modifications were also incorporated, and the scientists now believed they had the weapon that would blow away any remaining doubts about Britain’s credentials for membership of the megaton club. But it was still an experimental weapon and was so unstable that a file supplied with the weapon emphasised the absolute requirement that the bomb could only be assembled under the strict supervision of scientists from AWRE. RAF Wittering, home of No. 49 Squadron was where the bomb was to be loaded aboard one of the distinctive white-painted Vickers Valiant bombers, for its 10,000-mile journey to Christmas Island.
Now the bomb was lying on its side in a snow-drift on the A1. There were more than a few heads-in-hands in Whitehall that night. William Penney must have been in despair. Oulton, if he had known about it, doubtless would have blamed the Witch’s Curse. Much to the relief of the assembled scientists, there appeared to be little damage to the awesome weapon. The Operations Record Book at RAF Wittering for 26 February 1958 states:-
Owing to heavy falls of snow, a convoy from AWRE was stuck in a snow drift at Wansford Hill at 1500hr. An officer from this unit was sent to investigate. At 1700hr the vehicle was still unable to be moved. Rations and bedding were sent to the convoy from AWRE and an officer and a team of airmen were detailed to stand by throughout the night to give help if required. It was not until the following day that vehicles began using the A1. The convoy arrived at the main guard room at 1200 hr. Personnel were sent immediately for a meal. Unloading was commenced at 1400hr…”
The measured tone of the report was in stark contrast to the way James Challinor, a local garage owner, who was put on standby with his pick-up truck on the afternoon of the accident. He recalled: “I was in my workshop when there was a tremendous hammering on my door. When I went round I was confronted by a group of armed soldiers in a land-rover. They said they needed my pick-up and I followed them up to Wansford Hill. By this time the weather had really closed in and it was dark. Up ahead I could see some considerable activity. There were vehicles all over the place with lights flashing everywhere. Men were waving their arms and shouting orders; there was a hell of a flap. It was chaos.”
Mr Challinor was ordered to wait some distance away, but he could clearly see a ring of armed servicemen surrounding a lorry that had pitched into a ditch. He was eventually told that his pick-up wasn’t required and that he could go home. He distinctly remembered one of the soldiers cautioning him not to talk about what he had seen. It was only years later that he learned what had happened. He recalled: “I had no idea what it was all about at the time, and no-one told me anything. But if I had known then what I know now I would have gotten out of there as fast as I could, armed men or not.”
Of course the device was not armed: there was no way there was going to be a mushroom cloud blooming over the Cambridgeshire countryside that snowy afternoon. But unless the British government is prepared to open up the archives, there is no way of knowing if the fissile core had already been installed. The assembly work for the bombs was usually carried out on Christmas Island, but Grapple Y was such a special bomb that it is possible that only the firing mechanism had to be installed. To give some idea of what could have happened, you only had to look at a terrifying event that occurred just two days later involving two American bombers at the Greenham Common air base.
At 4.25pm on February 28, 1958 a US B-47 aircraft awaiting take-off on the runway was engulfed in fireball when a wing-tip tank carrying 1,700 gallons of fuel from another B-47 flying overhead was accidentally dropped. The fuel tank landed just 65 feet behind the parked aircraft, igniting on impact and engulfing the plane. Both aircraft were from 310th Bomb Wing (part of 3909th Combat Support Group) which carried Mark V nuclear bombs with yields up to 60 kilotons. Each warhead had a plutonium core surrounded by enriched uranium and TNT high explosive. The enriched uranium is used to increase the bomb’s yield.
If there was a fire both the enriched uranium and plutonium would be released in the form of a deadly oxide powder. Both aircraft were destroyed in the fire which was allowed to burn out because of the intensity of the blaze. The base commander Colonel Arthur Cresswell issued a denial that nuclear weapons were involved. That isn’t surprising as the British and US governments in top secret protocols agreed in 1956 to always deny that nuclear weapons were present in any accident involving American nuclear bombers stationed in the UK. These agreements surfaced in 1976 after details of another crash involving a B-47 which exploded in a nuclear bomb storage bunker at RAF Lakenheath.
Suspicions about nuclear fallout from these accidents have lingered ever since. Environment groups like Greenpeace have evidence of leukaemia clusters associated with both areas.
Penney and his band of Aldermaston weaponeers must have feared the worst as they later examined their prized bomb in a hangar at RAF Wittering. But the safety harness around it had done its job and Grapple Y seemed to be none the worse for its mishap. It was later flown safely to Christmas Island in plenty of time for the intended firing date.
No-one, not even Penney, was sure just how big Grapple Y was likely to be: estimates ranged from 2.5–7 megatons. But they were taking no chances. Thousands of anti-flash hoods, gloves and white boiler suits were provided for the men on the island. Lessons had been learned from Grapple X and special attention was given to the effects of the blast wave on buildings. To avoid damage, loose items were to be secured; all glass windows, doors and partitions were to be removed and all electrical equipment not essential for the test switched off. Cupboards had to be laid on their sides. Pets were to be rounded up and put into containers; efforts were to be made to round up any stray animals. All tents were to be vented and furnishings tied down.
It was a very worrying time for all the scientists involved; Penney also had the added worry of keeping his own involvement as secret as possible. Whether he liked it or not, by this time he had become an international celebrity. He was flown round the world in his own specially converted Hastings aircraft and given VIP status wherever he went. His aircraft was always ‘parked’ in areas reserved for world leaders and even the Australian premier complained because he had to be ‘vetted’ by Penney’s personal armed guard before meeting him.