An Army bomb disposal expert from Oxfordshire died after being buried alive exploring a First World War trench.

Lt Col Michael Watkins, 51, was part of a crack team surveying tunnels at Vimy Ridge, near Arras, in northern France.

The married dad-of-one from Standlake, near Witney, was checking that old ammunition dumps were no longer dangerous. The tunnels, on the site of a battlefield where 60,000 troops died, are thought to contain a large number of unexploded devices.

The accident happened after Lt Col Watkins dug a pit to investigate the opening of a tunnel near the Canadian Military Cemetery.

He died when the mouth of the tunnel collapsed on top of him.

A Ministry of Defence spokesman said: "The death of Lt Col Watkins appears to have been a tragic accident. The tunnels are a quite complex system and nobody really knows where they all are. Part of this work involved the surface survey of mine and tunnel entrances.

"It appears the ground gave way during this work. There will be a full investigation."

Lt Col Watkins, head of safety at the Directorate of Land Service Ammunition in Didcot, was one of Britain's leading bomb disposal experts - and was once hated by the IRA for his work in Northern Ireland. He was taking part in a joint British and Canadian operation called Operation Deep Charge Five during his spare time. The project was being filmed for a BBC documentary. Producer Marc Sinden, son of actor Sir Donald Sinden, said: "This man was the one true hero I have ever met. He single-handedly saved more lives than I can possibly imagine."

Earlier this year, Lt Col Watkins successfully defused a 6,500lb Durand mine in one of the tunnels. He personally trained the team surveying Vimy Ridge and had uncovered a 20-mile network of tunnels.

The tunnels, a legacy of the battle of Vimy Ridge in April 1917, were said to be "littered" with leftover charges, including one under a motorway and others beneath the Canadian memorial. Lt Col Watkins and a junior officer colleague were six feet underground when the tunnel collapsed. The junior officer managed to scramble out.

The full extent of Lt Col Watkins's work is now expected to be made public. Mr Sinden said: "His work was often secretive and undercover, and it would have put him in danger to publicise his action while he was alive.

"Now he is dead it does not matter. I admired him more than anyone I have ever met and I want people to know what he did."

Shocked neighbours near the family's home in Standlake were today trying to come to terms with the tragedy.

One said: "They seem a very nice, ordinary family who pretty much kept themselves to themselves," said one.

"It's a terrible thing to have happened."

Col Watkins had lived with his wife Rowena and son Robin, six, in Standlake for about five years.

People in the village described them as a pleasant family who kept themselves to themselves.

Robin is a pupil at Standlake Primary School and his mother helps with the parent teacher association known as the Friends of Standlake School.

The school's secretary Dilys Peach said: "It is an awful tragedy. I never met Col Watkins and had no idea of what he did but his wife is a very pleasant lady who helps a lot in a low key way and is very supportive of the school."

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