I knew the off side front wheel bearing was on its way out, there was a little play & slight rumbling when I span that wheel before the road trip, but saying "It'll be fine" I adjusted it up & drove off into the Welsh hills.
And indeed it was fine, I checked the wheel regularly & although the play had come back, it got no worse. I've just looked at it with the intention of fitting alloy hubs (but they only make them for RS struts - why?) & yes the rumbly off side one is probably nearing the end of it's useful life.
New ones on order from Burtons.