It is very likely an ex military bike/combination.
The MC sports the side welded oil tank (a later war period model), a wide toolbox (never used on civilian MC's)and the front fork shock absorber adjustment is by nut and not by a handwheel. A typical military configuration.
Only civilian 1939 model year Nortons had the front brake drum on the right hand side.
Every military built Norton built between 1935 and 1945 had the front brake drum on the left hand side.
16H sidecar combinations were mostly used by the RAF/RCAF/RAAF/RNZLAF and also by International squadrons in England like 320,322, 323 Dutch squadrons etc.
Army and Navy will have used them as well but not in large numbers.
