Kit bashing.
Scratch building.
RMwebing.
LNER OO gauge.
Some LMS and GWR.
Building exhibition layouts.
Long walks in the snow at night.
Throwing rocks at campers and avoiding humans with cameras.
You could try the www.stationcolours site. It will at least give you the info for the LNER and GNR, though what livery particular buildings were in the 1940s may be hard to establish.