Thanks, Mrs Wayne!
Well, I had the tests done today, and FWIW, the cardiologist pretty much agreed with you. Apparently the RBBB hardly even showed on the ECG, but the computer said it was there, and once it's found, you have to jump through the CAA hoops. Everyone seems to agree that the CAA want to be seen to be checking everything out as carefully as possible. They didn't find anything, and all that happened was I came away £380 poorer, with aching knees from the exercise test (nearly 10 minutes, then I gave up; at 5ft 2ins I was running rather than walking as you're supposed to by that point; my legs weren't long enough!). But I still have an OML on my Class 1 (and an unrestricted Class 2) for a year.
Oh well, I make more money from writing about aviation than practising it anyway, so I'll instruct unpaid for a year to keep up my hours. Could be worse.