While doing the clutch on a Rover 45 I discovered it has a really simple heater, just a plastic straight through cable operated valve that fits inline with the heater hose -- really neat.

my old audi 80 had the same...

The older rovers have them too and IIRC mini's do aswell.

[Edited on 31/5/06 by Danozeman]

Yup, a mate's rover mini has just the part you're on about. Quite small inline sliding valve jobbie.

Defo not a Smiths Industries sliding job, they were leak prone and tended to be very stiff in operation --- this valve is much neater and smaller.