MIG wrote

a) On national rail (where pre-pay is not yet valid) Oyster
readers are
often provided at (gated) London Termini but not at suburban
stations.


More likely the other way round on SWT, where Waterloo has no gates
but many suburban stations do (not just the ones shared by LU).

Not 'many'. SWT states (in the free mag anyway) that they only have 19
barriered stations. Clapham Junction may not be 'theirs' but most of
the ones I am aware of are not 'suburban' or only technically so
(Woking, Bracknell, Farnborough, Windsor & Eton Riverside).

--
Mike D