The German sounding chap that you are enquiring about would be
Karl Wahnig, also called Jack Wahnig.
Sadly he has passed on now. Karl & I used to duet together at various gigs. He had an interesting life as he was in U-Boats during the war and was captured off the Canadian coast. He wound up as a prisoner-of-war in Regent's Park, but at the end of the war many of the POW's whose homes were in the Eastern part of Germany elected to remain here. He got a job as a GPO engineer and worked for the Post Office until his retirement. In his bedroom he had many photographs of his time in the German Navy and on the deck of U-Boats. He is often credited in books and on various TV documentaries for information and photographs. He preferred to be called Jack and not Karl after the war until the late 60's onwards.