I have a Winter 1936 WTT for the section.
Taking Culworth again, at that time the passenger service was even sparser and weekday departures were:
Up
Around 7.40 am the 5.30 am from Nottingham to Marylebone via Aylesbury passed Culworth, calling at most other stations
10.51 am to Aylesbury (9.35 am from Leicester)
2.36 pm to Marylebone via Aylesbury (1.20pm SX/12.55pm SO from Leicester)
Around 9.0 pm the 6.50 pm from Leicester to Marylebone via Aylesbury passed Culworth, calling at all other stations
Down
9.5 am to Leicester (6.40 am from Marylebone via Aylesbury)
1.55 pm to Leicester (1.40 pm from Brackley)
8.4 pm SO to Woodford (7.35 pm from Brackley, ran every day but only called at Culworth on Saturdays)
Around 8.40 pm the 6.26 pm SX/6.25 pm SO from Marylebone to Leicester passed Culworth, calling at all other stations
Around 9.55 pm the 7.30 pm Marylebone to Woodford SX/Rugby SO passed Culworth, calling at all other stations
Not much of a service at all, really.
Further south, on the Ashendon - Grendon Underwood line, Akeman Street had closed in 1930. Wotton had only two trains a day each way: the 6.8 am from Marylebone called at all stations, terminated at Wotton at 7.50 am and returned whence it came at 8.17 am, reaching Marylebone at 9.54 am. The 4.50 pm from Marylebone to Brackley via High Wycombe called at Wotton at 6.15 pm, and its return working, from Brackley to High Wycombe at 7.55 pm, called at Wotton at 8.25 pm. Thus it was possible for a determined resident of Wotton to travel to London and return the same day, provided they wanted to do business between around 10 and 4.30! There was of course a much better service available from not too far away at Quainton Road, although since the previous November it no longer connected with Brill branch trains. Remarkably, the passenger "service" at Wotton clung on until 1953.