Stagecoach Charlbury bus timetable changes
From August 13 2017, there are a few important changes to the no 7, N7 and S3 routes to and from Oxford on weekdays and Saturdays. There will be one early morning, one evening and one late night journey between Oxford Parkway and Charlbury, Spelsbury and Chipping Norton.
Stagecoach summarises the changes here: https://www.stagecoachbus.com/service-updates/serviceupdatesarticle?SituationId=ID-29/06/2017-11:46:40:119
This means that it should be possible - at least in principle - to leave Marylebone at 23.10 and still get home to Charlbury by public transport by 01.07. The timing is, however, tight, given that the no 7 bus does not drive up to Oxford Parkway Station, but stops nearby on Oxford Road. Leaving Marylebone on the 22.40 would be more comfortable.