Video from Watford Junction in summer 1991 seems to show two (presumably northbound) night trains:
The first one is at around 4:15, hauled by a Class 87 and has a pretty weird formation of 2 Motorail GUVs, 3 SLE/SLEP, 1 TSO, 2 BSO with the van areas facing each other, 2 TSO. Strangely large amount of seating cars for a night train of that era.
The second one is at around 10:25, hauled by a Class 90 with a formation that looks like 4 Motorail GUVs, 6 SLE/SLEP, 1 RLO, 3 SLE/SLEP, TSO, BSO - which from what I understand was the standard Anglo-Scottish sleeper formation at that time.
The last-mentioned train is pretty certainly the Euston - Glasgow sleeper, or possibly the Euston - Edinburgh one. But the first one makes little sense with the large number of seating and the weird placement of the BSOs. Possibly the rear two TSOs + BSO are extra stock added for transfer to Scotland? Or the one BSO is to make up for a lack of a TSO? Or is it some sort of charter service?
The second one is at around 10:25, hauled by a Class 90 with a formation that looks like 4 Motorail GUVs, 6 SLE/SLEP, 1 RLO, 3 SLE/SLEP, TSO, BSO - which from what I understand was the standard Anglo-Scottish sleeper formation at that time.
The last-mentioned train is pretty certainly the Euston - Glasgow sleeper, or possibly the Euston - Edinburgh one. But the first one makes little sense with the large number of seating and the weird placement of the BSOs. Possibly the rear two TSOs + BSO are extra stock added for transfer to Scotland? Or the one BSO is to make up for a lack of a TSO? Or is it some sort of charter service?