Hi Wagonman, I have numerous pics of what looks like D109 ex B and D set coaches in BR days, 50s, which is the period I will model. In later years they were broken up from their formations and standard buffers fitted so they could be run as singles or formed up. Some of the pics show the two brake ends together which looks weird. Yes they did run non fitted auto coaches and also ex slip coaches too. Yet to find dia numbers on those.
They also ran a variety of stock as fillers too, between the D109s. Not sure if they ran the later D147s with standard buffers, just no pics yet.
Cheers for you help, Derek.