Well the funny thing is that the motor was running lovley and quiet, so there are 2 possibilities.
1. At the last dealer service they let the apprentice adjust the tappets and he screwed them down to far, (unlikley! because I know what dealers are like and they wouldn't go near them unless it was rattling, as possibly not even then)
2. A faulty hydraulic tappet that was not maintaining pressure so not opening a valve properly.
Either way they're liable because it's been dealer seriviced up until the last interim service, which would not require a clearence check!
They just come up with any excuse :roll: