In message , Peter Smyth
writes
It seems all the London-bound trains are operated by South Central,
anyway.

Actually there are two TOC's at Leatherhead, South West Trains to Waterloo
and South Central to Victoria.

The SWT trains ones must be consistently slower than SC, then - they
don't appear on the Railtrack planner if you ask for a journey to
London.
--
Roland Perry