WZ877:
I can't help with the precise colour matches, but when my Chipmunk "box of bits" arrived here in 1996 there were FOUR shades of red present on the airframe!
Also, if you're talking about 1973 then you're looking at the first, less common, permutation of the Red/White/Light Grey scheme. This comprised the red/white fuselage; wingroots panels, wing leading edge, wingtip in red with all fabric areas grey; tailplane is red but elevators in grey. Only a few RAF Chipmunks wore this scheme, whereas the entire fleet eventually ended up in the post 74 scheme (wing outer panels red and elevators red, wingroots grey).
Perhaps this explains it better (but note that the shadow hides the upper aircraft's red wingroots)
