So, for a (I think) complete list:
GWR: 2, 3, 4, 5, 6 (rare), 8, 9, 10, 12
SWR: 2, 3, 4, 5, 6, 7, 8, 9, 10, 12
XC: 2, 3, 4, 5, 6, 7, 8, 9, 10
Southern: 2 (rare), 3, 4, 5, 6, 7 (rare), 8, 9 (rare), 10, 11 (rare), 12
Great Northern: 4, 6, 8, 12
Thameslink: 8, 12
LO: 4, 5, 8
Southeastern: 3, 4, 5, 6, 7?, 8, 9?, 10?, 11?, 12
C2C: 4, 8, 12
tfl rail: 7, 8?, 9
GA: 3, 4, 5, 6?, 7?, 8, 10?, 12
LNER: 5, 9, 10
Hull trains: 5
Grand Central: 5
EMR: 1?, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12
AWC: 5, 9, 10, 11
Chiltern: 2, 3, 4, 5, 6
WMT: 1, 2, 3, 4, 5, 6, 8, 12
TfW: 1?, 2, 3, 4, 5?, 6?
Northern: 2, 3, 4, 5 (rare), 6
TPE: 3, 5, 6
Merseyrail: 3, 6
Scotrail: 2, 3, 4, 5, 6, 7? 8
Caledonian sleeper: 4, 5?, 6, 8, 16
Eurostar: 16, 18