Stafford has a p2, the southbound bay next to the toilets on p1.
Stratford's p4/7 were for the Fenchurch St shuttles via Bow Rd, which ended around about WW2. They were consequently filled in, but have reappeared elsewhere - the old DLR platforms were 4a and 4b IIRC.
As 90019 says, 5/6 at Edinburgh were used for the Motorail.
Nottingham has 6 platforms, none missing, p2 is the bay for Skegness services.
Add to list:
West Croydon - p3 bay for Wimbledon now filled in (Wimbledon line is now the Croydon Tramlink).
Twickenham - p1, in situ but disused and unnumbered, similar to Aberdeen p1/2.