The Buffet murals were in 4-BIG's from quite early on.....there is a photo(black & white) of the inside on P.126 of the 1979 'Railway World Annual' where they describe the graphics at least as banal!
Personally I quite liked them.
The only slight doubt I have was according to my memory at least I do remember the Black/White/Red combo's but not the Blue/White & Red.