RMcB

Thanks for all your help. All is well with the horn now thanks to the great advice and knowledge on this forum.

Quick recap:
- Bought TF, horn doesn't work ( airbag seems fine though)
- Changed all relays, no change.
- Consulted this form, changed MFU (no change), bought wrong rotary coupler.
- Consulted this forum again, and realised that the rotary coupler in the car physically fits, but is the wrong one.
- Changed rotary coupler to the correct one - peep peep! Hooray!

- Two weeks ago knew nothing about nothing. Now I know a bit about MG TF Lucas electrics.
- How did the car pass an MOT without a working horn six weeks before I bought it? Was it broken and inexpertly "repaired" in the intervening six weeks?

Thank you all again who contributed. I'm sure that I will continue to try to alleviate my ignorance on this forum.