I thought by swapping the relays that would make it an unlikely candidate… but it’s true that I don’t hear a click on activation, assuming it would be obvious enough that I can’t miss it like the click from ignition when it fails.
I’ll run throught this to test the relay shortly: Horn not working need new ideas to test - #2 by Roadster_Robbie
Unfortunately it needs to be re-MOT’d by the end of the week and unless a dealer has an LA10 relay I’m short of time to wait for one and find out if it works.
Except possibly pulling one from a scrapyard, never quite followed how exactly one does that.