British POW in Bergen Belsen

I am trying to find information regarding British POWs in Belsen. My Step-father Ernie Harris (now deceased) was captured by the Germans around September 1944, I guess during the Normandy breakout, and was shipped by train to Belsen. He remained there until liberation in April 1945. He was with several other members of his tank crew (he drove a Sherman) but was the only survivor. He was shipped back to England to a hospital in the North where he was kept sedated for several weeks - he weighed 5 stone when liberated! The only reference I can find about a British POW in Belsen relates to the Special Air Service looking for Allied POWs hours before the official liberation of Belsen. The man they liberated was called Jenkinson. Whilst convalescing in England, Ernie was asked to write an affidavit against Josef Kramer, I cannot find any reference of this either. Sadly my Step-father is no longer with us and I regret not writing down more detail from the stories he told me at the time. He did have a number tattooed on his left arm when he arrived at Belsen which he later covered with another tattoo and he told me that a Jewish doctor helped him after he had been stabbed through the hand with bayonet by a German guard when he tried to get a potato that had fallen on the floor from a food trolley. The doctor told him to urinate on the wound to keep it clean and disinfected, which he did and it worked! It was nearly 50 years later before Ernie spoke of his ordeal in Belsen and his story of his involvement in WW2 was fascinating, from training on Sherman tanks in Scotland, where he got one stuck in bog and it sank from view, his landing on Sword Beach on D-Day, the battle for Caen, crouched in a fox hole all night with his best mate whilst the Germans shelled their position with mortars and wishing they had dug it deeper!, his capture and time in Belsen. One humorous note: during his stay in the convalescence hospital in England he sneaked out to the local pub for his first pint of beer, he drank about half a pint and passed out and had to be carried back to the hospital by a couple of locals.