I've taken a look at my copy of the 1974 edition of the RCTS Coaching Stock which lists 22 LMS-design sleeping cars and 7 LNER-design buffets still in service at the time as follows:
LMS-design sleepers SLSTP-type built 1951/2: 601-624 except 605 & 610 (all dual-heated and allocated to the LMR)
Gresley-design buffets built 1936/7: 9115, 9128, 9131, 9132, 9135 (all steam-heat only and allocated to the ER except 9135 allocated to the WR)
Thompson-design buffets built 1948: 1705, 1706 (both steam-heat only and allocated to the ER).
There were still many pre-nationalisation NPCCS vehicles in use at the time, for example there were about 450 LMS-design bogie full brakes and about 900 SR-design four-wheeled PMVs and CCTs. Some stock had build dates well into the 1950s, for example GWR-design Siphon Gs went up to 1955 and LMS-design CCTs up to 1957.
LMS-design sleepers SLSTP-type built 1951/2: 601-624 except 605 & 610 (all dual-heated and allocated to the LMR)
Gresley-design buffets built 1936/7: 9115, 9128, 9131, 9132, 9135 (all steam-heat only and allocated to the ER except 9135 allocated to the WR)
Thompson-design buffets built 1948: 1705, 1706 (both steam-heat only and allocated to the ER).
There were still many pre-nationalisation NPCCS vehicles in use at the time, for example there were about 450 LMS-design bogie full brakes and about 900 SR-design four-wheeled PMVs and CCTs. Some stock had build dates well into the 1950s, for example GWR-design Siphon Gs went up to 1955 and LMS-design CCTs up to 1957.
