Rather than adding on to the end of an old thread I thought I'd start a new one with a recommendation for someone who can do this job at a competitive price that may be more suitably located for other owners (I didn't fancy trekking all the way to the south side of the M25).   I was talking to a friend who mentioned the oil gallery gasket failure and how it would present itself in both physically readouts and driving characteristics and unfortunately mine ticked all the boxes. -Low oil press