no lights on front of worcester heatslave 15/19?

It may be the fuse on the spur to the boiler, try another fuse (5amp for oil), if that blows there will be a problem with an electrical coil in the system (pump, fan, gas valve etc).
That would need properly checking by a decent repairer.

Being as it's a Worcester, it could however be as simple as an overheat thermostat, remove the front large cover, look up underneath the top panel towards the left there is a little pinkish/red button, press it, if it clicks it has activated and if doesn't activate again, should be okay

Carefree
October 2010