Hi,
RBBB can be present in normal healthy people, it can also represent right sided heart pathology.
I know one class 1 holder very well who is normal, fit and healthy but has RBBB on ECG. It was seen on renewal and he had stress testing and echocardiogram, which were normal.
I would suggest contacting the CAA medical lot at Gatwick and asking the question. Do you have a medical already or will you need an initial? Is this a new finding or have you been investigated re: underlying cause etc?
If you have a RBBB on ECG when you go for initial you'll most likely be asked to go for further testing, which if normal, as far as I know shouldn't be a barrier to a class 1.
Not definitive advice but hope that helps.
B