There is the normal half dozen or so clicks when the pilot lights then after a few seconds the pilot just goes out without any gas coming through to ignite the boiler. Then the sparking process begins again. The pilot lights more or less at the first spark every time. But it is not consistent sometimes boiler will light first time other times has taken up to one hour to light. Naturally I am wondering if it could be gas control valve or boiler control unit.
lit first time when started it upon getting home but has been playing up ever since thermostat operated cut off
do have multimeter
I take it I am going to have to remove the fire front to do this check
can't get at it from underneath so will have to dismantle
problem now solved. As I had to dismantle decided to have look at pilot gas injector. View from front is not good for judging pilot flame depth so dismantled blew through and has been right since. Thanks for help.