Searching the "real" grandfather

Someone asked me (as the chairman of Royal Air Force Museum Laarbruch) for help in finding his grandfather.
It’s a long shot.
The RAF unit was stationed in Germany, Haltern am See, in a hotel called “Overather Hof”(directly after the war – 1945 and 1946).
If anyone could name the RAF unit that was stationed there it would be possible to find out more.
The name of the Leading Aircraftman in the photo was Mark Stewart (or Stuart), may be from Scotland, Aberdeen.
There’s a photo of Mark Stewart (born 1924) with his German girl friend Regina Kocik. Before she got his baby in November 1946, Mark was detached in September.
The family didn’t like the idea of a non-marriage child. So another “father” was found. Everybody kept quiet about this story until a few weeks ago when Grandmother suddenly died.
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