(OT) A waste of money though - surely Thameslink still exists as the
name of the National Rail route.

It does... but it's far less prominent now. The trains don't have it written
on them any more and announcements etc. don't mention it. Besides which,
once the Thameslink work is all finished, the thameslink route could mean
trains to any number of destinations rather then the fairly simple route it
refers to at the moment.

Best Wishes,
LEWIS