Have effected temporary repair with blue hylomar this evening as i need to stop the leak before going down to Monthlery Vintage Revival in a couple of weeks.
The problem appears to have been that the rocker cover securing screws had loosened with vibration over the 7000 miles the car has done. The screw at the leaking area was finger tight and when i looked at the other cover, several of those took a gentle tightening.
The original installation of the gasket was with a dark rubberish sealant, but the coverage was patchy and none in the area of the leak.
