Are there a lot of working antique steam trains in England?

I watch a lot of British period pieces, and there are often scenes in which a (non-modern) steam train pulls into a station. I’ve often wondered if there are a lot (or some, or even any) real, antique steam trains in the U.K. that are used in these movies and TV shows, or whether it’s all just C.G.I. and illusion.

I really like trains, although I wouldn’t be able to tell one from another, or whether the ones I’m seeing are replicas, or real trains, or simply computer generated trains. I hope they’re real.

Do any of you Brits, or anybody who has been to the U.K., know anything about the antique-looking trains you see in movies and TV?

The most recent example of one of these trains was from the TV series Father Brown.