Prior to the mid eighties Craven coaches always ran mixed with other coaching stock with the cravens normally marshalled together within that formation .
This picture by Jonathan Allen from flicker illustrates the point a very typical train containing two cravens to the rear of the train with various other coaching stock mixed in .
The make up of the train is behind the loco is(open to correction ) a Park royal ,a 1356-1371 std open , a 1429-1448 laminate , a 1904-1908 brake standard , 2 Cravens , a 24xx buffet car and a Dutch van 3157-3166 steam heating/gen van at the rear. The two cravens and the Buffet Car are most likely TL (220v supply ) coaches and necessitate being marshalled next to the Dutch van while the older coaches towards the front are possibly battery dynamo powered systems .