"D" P.doody@monkeynuts wrote in message ...
I think you might have misunderstood what Tim Mitchell meant. You remove
that white plastic cap - it's just a cover for the bleeding valve. Lift it
out and insert your key.

You are both right, the little plastic cap was indeed a cover for the
bleed valve, the only radiator in the house to have a cap over the
bleed valve but I still feel stupid for not realising. Thanks all for
your help, much appreciated!