Glow-worm F55 Fuelsaver boiler: pilot light not firing?

Hi. Just come back from holiday and my boiler has stopped firing up. This happened before, lots of rain damped out the boiler. It was cutting put the RCD, Left it a week last time then it fired. Same story this time, but dried the unit with a hair dryer: the boiller now partially fires up, the fan runs and the spark is trying to fire the pilot light. Is there a saftey switch that may have popped? Does anyone recognise this fault?