I have just bought a house which has those wierd radiators where the very small valve is situated on the back of it (I can't find a brand name anywhere). Standards keys are much too small to fit the valve which is approx 4mm in diameter. Please can anybody advise where I can obtain one of these?

Charlie, January 2008

The valves are square and are too SMALL for all the keys found on the high street (just noticed the typo in my question!)

Charlie M, January 2008

Its not a rounded off normal one is it Charlie?

John, January 2008