David Biddulph wrote:

Which of those have red trains today?
--
David Biddulph

As far as I know, the only red multiple unit trains anywhere in the
Greater London area are SWT's refurbished class 455s, and they aren't
completely red, and they aren't underground trains either.

I did read somewhere that before 507s & 508s took over completely, one
of the LMS type Merseyside emus which had been painted into period
maroon livery, had been used in a film or TV drama to represent prewar
LT surface line stock.