Finally bit the bullet and rubbed back through the layers of 2-pack etc. etc. (well, Colin L did) on the Mk.5 bonnet. The cracks are horrendous and widespread and deep. It's only to be expected I suppose, it's pretty old. Maybe it's had a hard life, I wouldn't know. That 2-pack is pretty hard stuff. It'll all be OK in the end when it's glassed up.