In uk.legal D.S.B. wrote:

I notice at Birmingham New Street that a small
army of people are now employed to check tickets at the exits/entrances
although they only glance at them without any detailed investigation.

Also applies at most 'Virgin Trains' stations- like Euston, where they just
clip anything you put in front of them, particularly if there's a rush.

Euston? I have seen ticket checks for local journeys. But not
for entering/exiting the Birmingham/Wolverhampton train.

At KIng's Cross it was a different matter... but then I was
commuting to Edinburgh usually that station it would have proved
platform ticket checks impossible. Bizarre, I remember a journey
to Germany which I took... no problem with having a drink at Waverly
at 7am... rather different in Newcastle at 10 am.

Axel