Rest easy, Detlef, the wiring is all fine - I have checked it all. The fault must be with the pump. I have isolated the fused outlet from the control panel that the pump uses from the main supply and left that on its own on the panel fuse as there a fuse in the English plug anyway. So at least the lights work OK and the pump will then now have its own, secondary fuse. Just need to fix the pump and remember to buy a 220V 20mm glass fuse appropriate for the rating of the pump.