When the Westerns were built, most of their trains were in the maroon livery, as were the bulk of the locomotives as well, so they matched. When the blue/grey rolling stock livery came along, the locomotives changed to blue as well (one of the few colours they had not worn before, there having been red, green, yellow and golden-coloured ones at first).
The brown/cream coach livery was confined to "named" expresses from the late 1950s, generally just one or two per route, although it wasn't particularly consistent, maroon vehicles mixed in were common and odd brown/cream ones elsewhere even more prevalent. Only a small percentage of the WR fleet was painted brown/cream, everything else was maroon. Well into the diesel era a common Western Region approach to busy services was to add an old Hawksworth GWR coach or two as the last vehicle, which typically added a different livery at the back of the named services.
