Thanks but it is the permanent pilot light going out that has coincided with the boiler not working.
The reset switch has previously reignited the pilot light and led to the boiler working.
This has not happened this time and the pilot light is still out. Surte looks like the boiler only works when the pilot light is lit.
I will call for mainteneance (from the manufacturer) tomorrow.
Thanks anyway.
Michael, Streatham
February 2009