sounds like the diaphragm has split in bottom section where 6 bolts run round in a circle, from memory u will need a 7mm spanner to undo these and a new diaphragm which should be readily available at most plumbers merchants. turn water off and open taps before u start.
keithh1968
March 2009
Sounds like the pilot is partially blocked or if not it is the thermocouple
andy
March 2009
I can answer this question...
How can I fix my water boiler- Britony II T model?