‘Boeing Brown’, was perhaps a contribution to attempts to differ from Airbus, particularly with the success of their Porsche designed flight deck. Thus ARINC avionics manufacturers were encouraged to provide the alternative colour.
Similar options were provided for GA aircraft.
BAe were approached by prospective customers to provide a brown flight deck for the DH125. ‘Good grief’, no way - ‘Elephants Breath’ Brown !
These views were supported by comparative investigations on the effect of flight deck background colour; mainly in support of Airbus work. However, some US completion centres did provide a brown flight deck for the 125.
One deviation from the conventional brown was that for a notable wax company - brown boot polish, where the flight deck and cabin were furnished in brown (suede) leather.