Chester to Oxford can currently be done in 2hrs 41m, with a straightforward change at Stafford. Milton Keynes is an hour and a half from Chester, plus a penalty for actually stopping there (currently you don't). Milton Keynes to Oxford is supposed to take something like 45 minutes? Then add an interchange penalty which at a minimum will be five minutes, but could be anything up to 34 minutes depending upon how the timings line up. The time saving is potentially non-existent.
Potentially non-existent - or potentially existent.. at the same time. The Schrodinger railway
Here's how it would look currently - northbound.
MKC-CTR timings: hourly 1h50 (15 mins past the hour), hourly 2h23 (19 mins past the hour), hourly 2h18 (24 mins past the hour)
OXF-CTR timings: hourly 3h4 (39 mins past the hour), best 2h55 (12 mins past the hour, some hours per day).
So, theoretical best (0 min conn at MKC) - 2h35.
OXF-MKC shadow timetable 45 mins, at 10 past and 40 past the hour - arrives 55 past 25 past the hour.
That gives you an hourly OXF-MKC option at xx.10 for a CTR departure, the xx.50 arrives too late for everything.
Concretely the three options to CTR between 11am and 12pm:
- 10.38 OXF-BHM (a. 11.51), 12.04 BHM-CRE (a. 13.00), 13.21 CRE-CTR (a 13.42)
- 11.10 OXF-MKC (a. 11.55), 12.15 MKC-CRE (a. 13.24), 13.45 CRE-CTR (a. 14.07)
- 11.12 OXF-BHM (a. 12.16), 12.34 BHM-CRE (a. 13.30), 13.45 CRE-CTR (a. 14.07)
However, the xx.10-ish CrossCountry runs only some of the time.. after 11.12, the next one's at 15.10..
In a nutshell - if XC restore the hourly, XC always wins by - price will be a factor instead.
Assuming OXF-MKC is opened _before_ those service are restored - then for ~30 mins per hour (xx.39 to xx.10) the best departure is via OXF-MKC, and for the other ~30 mins (xx.11 to xx.38), the best is OXF-BHM.
I did a similar post for Liverpool / Manchester to Oxford a couple of months or so back.
The other benefit is the last train - MKC-OXF may run later than BHM-OXF (last train 22.03), or ex-Moor St (22.20).