In a roughly chronological order:
Liverpool St to Chingford, c. 1958 quint art pulled by N7
Aldgate to Watford (Met) c. 1960 in 'T' stock EMUs
Barking to Kentish Town, 1959 hauled by Stanier 2-6-2T
Wien Westbahnhof to Oostende (via Passau), 1963 return from school trip in couchettes
Liverpool St to Norwich, 1964 probably class 40+Mk1s and Thompson steel coaches
Waterloo to Portsmouth Harbour, late '60s/early 1970s (first couple in 4-COR stock)
St Pancras to Bedford 1986 (network day) in class 317
Fareham to Waterloo, 1991 in 4-CIG
Kings Cross to Edinburgh Waverley, 2006 in MK1Vs hauled by class 91
Bedford to Brighton, 2016 on first day of class 700s through core
Various other mundane journeys on branch line stubs in the south-east throughout the same period above.