2P20 didn't call at Oxford. 1P07 was awaiting its driver off 1D03, which was delayed due to earlier issues with a freight train.
I hope the driver for 1P07 isn't normally booked to travel down on 1D03 which is booked to arrive at Oxford at 0620, thus allowing just 10 minutes to get over to P1 and depart with 1P07. Doesn't give much resilience against late running. But maybe they were short of train crew and improvising this morning.