Simon Glancey has submitted the following:
Flight Lt. Nicholls was the pilot of Short Stirling I BF387 MG-U of 7 Squadron, which was lost on a mission to Hamburg. The Stirling crashed into the North Sea - the body of one of the crew was washed up on the island of Sylt, but the other six crew members were lost without trace.
Royal Air Force Bomber Command Losses of the Second World War: 1942; W.R. Chorley; 1994; Midland Counties Publications; ISBN 0 904597 89 X, page 258
His D.F.C. had been gazetted in the London Gazette on August 11th 1942.
Also killed in the same incident was Sgt., D.H. Davison
Tony Hibberd has offered the following:
Stirling BF387 MG-U had departed Oakington at 1719 for Ops Hamburg.
It was engaged by Marine Flak and 2/lei Res Flak Abt 836, hit and shot down
The aircraft crashed into the Sea near Puan Klent at 2006Nachtjagd Combat Archive The Early Years Part 3 Dr Theo Boiten
Walter Nicholls is remembered in Bishop Auckland on B140.01 and at Willington on W120.02