Is one still expected to tip taxi drivers in Britain? If so, how much?

10% unless they do something egregious, sometimes more if they’re really good. It’s really not that great a job at times, and with fuel going up by the day and fares fixed, I’ll keep tipping as long as I can afford to keep taking taxis. Waiting staff are also paid a (more) sensible wage here - some of your arguments would seem to imply that we shouldn’t tip them either, e.g.

but I don’t know anyone who wouldn’t.

I had him keep the change, which was 60p on a £16.40 fare. He seemed a bit surprised and genuinely grateful.

No I’m not in London, I work in a fairly rural part of the country.

We do have a knowledge test but it’s fairly basic stuff, a few questions on shortest routes between two places, location of schools, hospitals etc.

The knowledge that the London guys do takes years to learn.