I have a Stelrad Ideal W Gas Boiler, & last night it decided not to spark?

It seems that the boiler is coming on, the main dial, clock and switch all appear to be running fine, there is the normal hum / click noise when you start it, but there appears to be no spark to ignite the flame in the boiler itself, so unltimatly no flame at all..???
Not sure how i sort the spark out, the gas sounds as though its working, and all the other gas related items in the house are working fine.?
I have even checked the main fuse etc but nothing.?
Any suggestions as its starting to get a bit parky..?????