Yes, the problem was the timing chain being a little loose and rattling against plastic guides. There had been at least two revisions to the chain tensioner to solve it. The latest chain tensioner and several other components had to be back ordered from Germany at the time. According to Mini was car was 'over' repaired to be on the safe side. Whilst installing the new tensioner they replaced almost everything else the chain came into contact with totalling just over £1,000 worth of parts.
Others on this thread had the new components installed and the noise returned though!
Mini is aware this is an issue, who knows if they have fixed it or not. As I've mentioned before I won't be 100% happy until the car has seen another winter.