The group went past the guards through a fence into the plant, Claus was on guard outside, "I was just sitting there, waiting, scared, thinking what to do if it went wrong. Then I heard an explosion. We were not even seen."  In fact the group had not had to fire a single shot.

3,000 troops were quickly sent to hunt down the saboteurs, the group made an epic 300-mile escape on skis to Sweden. Claus, however, was given instructions to pick up a consignment of arms, which had been hidden in a hut. The Germans had beaten him to it and he ended up being chased on skis for miles, "First there was seven, then three, then two, then only one left. I remember stopping, turning firing three shots, he fired back, then ran out of bullets. I then fired back and he ran away".

But luck was not on his side, "I was skiing in darkness, suddenly I went over a precipice and broke my arm. But I had to go on as I had a contact to meet, so I skied another 40 miles."

By the time he reached his contact's hut he had been skiing constantly since the day before. To his horror, the door was opened by a German soldier. "I started lying," explains Claus, "I said I had been guiding Germans." It worked.

The soldier sent him on a bus to Oslo to see a doctor. Then, during a stop at a hotel, a group of Germans came in and arrested every Norwegian staying there, bundling them on a bus to an internment camp. Claus waited till it slowed down then flung himself out rolling down a slope, and falling on his broken arm. But he was free again to fight the Germans until the end.

One of the group, Knut Haukelid later sank the Hydro Ferry loaded with a hundredweight of Heavy Water with the loss of a few civilians. This effectively stopped the production of an Atomic Bomb and saved many

Taken from the excellent four part documentary by the BBC TV and produced by Professor David Stafford, entries in William Mackenzie "Secret history of SOE" documents from the PRO, HS 2/172 and HS 2/184-185-186-187-188-189-190, my notes and conversations with various researchers.