When GNER refurbished all the fleet under “project Mallard” a lot of TSO’s were reclassified as FO’s to bring all the sets into the same formation. ( TSOE, TO TO TO TSOD, TBK, FO , FO FO, DVT) The buffet coaches were turned round so that the kitchens were next to the FO that was 1/2 restaurant, 1/2 FO. This is how the sets remain. In BR/Intercity days , when first introduced there weren’t enough M4’s to make up a full rake so some were 7+DVT and some 8+DVT. Eventually there were enough M4 TSO, to make up a full 9+DVT. The formation being. TSOE, TSO, TSO, TSO, TSO, TSOD, RFM, FO , FO, DVT (STANDARD FORMATION) and the others were TSOE, TSO, TSO, TSO, TSOD, RFM, FO FO FO DVT (PULLMAN FORMATION. ) I Believe Hornby Weill be doing the IC M4’s into an 8 car formation.
The GNER coach lettering would be A, B, C, D, E, G ( or H )K, (restaurant) L, M ( unless anyone knows different, I’ll stand corrected)