John B wrote:

It seems a bit of a draconian restriction set for a surburban operator
- the FGW rule where cheap tickets can only be used on slow trains
(effectively also the case on the WCML with the Virgin/Silverlink
split) is more reasonable.

Depends on capacity constraints - it may well be that the commuter
trains are more overloaded than the ICs.

There is a precedent to all this; off-peak tickets were not allowed
between 1600 and 1800 in the Merseytravel area for a long time. I have
a feeling, but might be wrong, this only applies to the City Lines
these days, as the Northern and Wirral Lines have a lot more capacity.

That said, all this could lead to an interesting fares anomaly, in that
an off-peak travelcard and a peak single back, or a SDR and an off-peak
travelcard bought separately, may now be cheaper than the available
through ticket.

Neil