That makes sense Arfa. I guess you just saved me trying to find my croc clip probes or risking blue lights!
In summary then, CFLs almost certainly save more energy than tungsten lamps when dimmed. It's best to buy all lamps from the same batch when dimming more than one to ensure they glow the same. Until they devise low power dimmers you must have more than one lamp or you won't load a dimmer properly.
Thanks to all for comments.
Peter Scott