Big Blast at Probus Club

Bramley resident, church warden and member of the parochial church council, Geoff Twine, gave an illustrated talk to the Probus Club of Basingstoke, of which he has been a member for many years, about two years of his life spent in charge of the world’s biggest bomb disposal task. Flight Sergeant Twine, an armourer by trade, had been based at the Bicester RAF Explosives Ordnance Disposals unit when he was given the responsibility for the Llanberis slate quarry project.

Pre-war had seen these disused slate quarries in North Wales, as the main RAF Bomb Storage Unit. They had been converted into huge underground bomb stores and during the war there was considerable activity in despatching all types of ordnance to the airfields throughout the country. Post war the area had been used as a disposal area where Bomber Command despatched thousands of tons of obsolescent and deteriorating stocks of explosives to be made safe or destroyed. It was decided to maintain the area as a storage depot for the bombs probably on the basis that there was nowhere else more suitable. When the RAF moved out in 1956 they attempted to destroy the explosives. Fires burned for days and explosions rocked the area.

The area is a nightmare of crags and quarries linked by tunnels and high mounds of dumped slate fragments. There were quarries 900 feet deep and others with lakes 60 feet deep containing 20 million gallons of water. It was one vast booby trap to the unwary. 10 foot barbed wire fences eventually erected around the site failed to prevent trespassers resulting in some injuries. In view of the upcoming investiture of Prince Charles as the Prince of Wales at nearby Caernarvon castle and the deteriorating situation in Northern Ireland it was decided, a quarter of a century after the end of the war that something needed to be done.

Because of the nature of the site men had to be trained in mountaineering and abseiling as this was the main method of gaining access to the now seriously decaying devices down the sides of the quarries. As they crawled along narrow ledges, some of them hundreds of feet above the bottom of the pits, they used all their skills and iron nerves they possessed to turn any bombs or explosives they found into harmless objects. The passage of time and rock falls meant that bombs were found on ledges or crevices and many now lay exposed on the quarry floors. Divers searched the lakes and discovered considerable numbers of ordnance that although being underwater still had the capability to explode. The lakes were drained before work could be started and the pumps kept going as there was a natural inflow from streams of 170,000 gallons a day.

In a Daily Mirror article published on 5th September 1973 Geoff Twine is quoted “We know what we’re handling and what it is likely to do. On a job like this we’re writing the book as we go…there’s no precedent.” And testament to the high professionalism of Geoff and his small team there was not one fatality during the years it took to make the quarries safe at what had been described as the biggest time bomb in the world.