On Tue, 14 Jun 2005 11:02:47 +0100, "Dave Plowman (News)"
wrote:

Most likely the thermocouple. That's the device which pokes into the pilot
light and has a thin copper tube going to the gas valve. It senses the
pilot light being alive and well and then allows the gas valve to open on
demand. If it's faulty, the gas valve won't open.

You'll get one from some B&Q etc, or any PM for a few quid.

I'm pretty sure that on these boilers, if the thermocouple fails then
the pilot light will also go out.

sponix