but it's no good just saying 'Cessna' or 'Piper'. We had a Cessna 150 and a Cessna 303 in the circuit a while ago
Surely "Cessna" and "twin Cessna" would have worked then, just like it does in the States.
We teach at a busy grass airfield in the UK, which is A/G and often all 3 of our C150/152s will be in the circuit together, plus any other based aircraft or visitors... I've taken to giving the aircraft paint colours on the initial call if I hear another one of our lot in the circuit and an "outsider" to give some idea of which one we are.
Most problems (in my mind) seem to be caused by people so desperate to get their calls in, that you'll get "G-XX downwind" when they have just turned onto downwind and aren't abeam the departure end of runway, and also "G-XX Final(s)" (why plural?!) during their turn onto final or even before then.
I would agree that hearing "Cessna BC final" or "Cherokee AD downwind" would be a miles better way instead of saying the "Golf" bit each time that adds nothing in the way of useful information.