Thanks for the suggestions allanjl, but I have already done both of those things. Distant shadows look acceptable, but ones close to the viewpoint are very jagged. In your example, move the camera close to the object, and see what the shadow looks like! Not nice, I can tell you.
The reference to 11 was my attempt at humour! People usually refer to things on a scale of 1 to 10, with 10 being the maximum, or the ultimate etc... Well, 11 is even beyond that. Anyway, I'll stick to my daily job, which, thankfully is not being a comedian!!