I think I would share John's caution if I had a freewheel, except possibly in slow town traffic. It says a lot for the change in approach to motoring that a device that requires a good deal of forethought in its use should have been available in popular cars. Frank, my Riley book is in storage while I wait to move into a new house, but i would be glad to lend it once I can lay hands on it again in a couple of weeks time.
Ciao
Cesare