War memorial upgrade plans for Scots who died trying to foil Adolf Hitler's atomic bomb, including Grangemouth soldier

More than 80 years ago, a group of Scots soldiers were sent on a mission to destroy the hydro plant where the Nazis had the power to create their own weapons of mass destruction. Only one of them made it home.

A war memorial in Caithness dedicated to the nine Scots, who were among 48 soldiers involved in the Operation Freshman mission, is to be upgraded as part of the plans.

But the hunt for living relatives of three of the soldiers, including one from Grangemouth, continues.

Historical researcher Dr Bruce Tocher, a Scot now based in Stavanger, has spent the past five years examining Operation Freshman for a new book.

He is attempting to trace the families of three of the Scottish servicemen and said it was a “tragedy” the sacrifices made by the men – and the horrors they faced – were so little known.

The servicemen in question are Lance Corporal Alexander Campbell, of Grangemouth, Corporal James Cairncross, from Hawick, and sapper John Hunter, from Lennoxtown.

On a freezing night in November 1942, the Allied soldiers had taken off from a tiny airstrip at AF Skitten, near Wick, in late 1942.

Jammed into two plywood gliders and carrying pocketfuls of explosives, they were charged with destroying parts of the Vemork hydroelectric power plant in Telemark in the south-west of Nazi-occupied Norway. It was here that heavy water – the material needed to make a nuclear reactor – was being produced in abundance.

But after a three-and-a-half hour flight – when the two gliders were each towed by a rope connected to a Halifax bomber in an operational first – poor weather and failings in the guidance system led to three of the aircraft crash landing in the Norwegian mountains as the ropes froze, took on extra weight and snapped in the sub-zero night.

Of those 48 on board, 41 died from either the crash landing, execution or murder by German army or security services.

Five Scots, the youngest just 20, died on impact and the further horror of war – and its crimes – awaited the survivors.

Families were left for years not knowing what happened to their loved ones sent to stop the Nazi bomb.

Tom Conacher, from Plains, near Airdrie, was a rear gunner in one of the Halifax bombers involved in the mission.

His daughter, Christine Macdonald, told the BBC: "Dad never really spoke to us about it [the operation]. I think that was because of the terrible loss of life."

Dr Tocher has been working with Caithness Voluntary Group (CVG) and Royal British Legion Scotland to refurbish Skitten's memorial, which bears the names of men killed in the operation.

Dr Tocher previously told The Falkirk Herald there had been “too many risk factors” in Operation Freshman. Paratroopers were considered, but thought too risky given the potential for a scattered landing. Gliders, which could come down relatively discreetly with all men and equipment together, were selected to land in an area marked by the Norwegian resistance.

Dr Tocher said: “It was the first time they used gliders in combat, first time they had flown gliders at night, it was the first glider tow they had ever made and to try and land on a pin prick in Norwegian mountains in November in the dark – well, there were are a lot of things against them.”

What we do know about Lance Corporal Alexander Campbell was that he was the son of Alexander and Catherine Elizabeth Campbell of Grangemouth.

His service number was 1923037, he was 24 and with the Royal Engineers, 261 (Airborne) Field Park Company,

He was executed by firing squad near Slettebø, on November 20, 1942 and is buried in Commonwealth Grave at Eiganes Cemetery, Stavanger, Norway.