I managed to get everything done that needed doing. First I jacked up the rear of Snowdrop and put her on axle stands to refit the rear section of exhaust. While the back end was up I started her up and put her in gear to trace the whining noise. It was defintely the diff. I've already arranged to have the pinion bearing and oil seal fitted at my mate's a week on Monday. The boot light was easily fixed. The switch just needed connecting and it worked. I removed the rocker cover, cleaned it up (inside and out) repainted it, fitted a new gasket and put it back on. The pic is the engine before I started on the rocker cover.