On 2 Mar 2006 15:30:17 -0800, "TheOneKEA" wrote:

There is a M-F but not Wednesdays! return train from Princes Risborough
to Paddington. Runs late morning (11.28) from PR and returns from
Paddington at 12.55. In the past trains have diverted to Paddington
during periods of engineering work at Marylebone.

I once heard that the train does not run on Wednesdays because that is
the day that NR are patrolling the track!

ISTR reading that it's because there's a once-a-week freight that runs
at that time...