Hi Rich,
Just looked at your trip report, we obviously covered some of the same ground. We got the Portsmouth - Caen ferry then train to Le Mans. We had intended following the Loire et Velo route up river but got bored with it after a 100 miles or so and ended up doing a big loop and coming back to Le Mans via Sammur covering 511 miles in total.
That windmill thing was built in the 1860's to pump water to the chateau at the top of the hill, it's got turbine blades like a jet engine. We stopped there and had a chat with a bloke who was working on the restoration.