The electrics on my 2004 Mk1 1.6 focus is going haywire. I've had a new battery and alternator (maybe unnecessarily) but the problem has only been getting worse.

 

The headlights keep blowing. All the exterior lights and the instrument panel lights flicker. The interior light switches on and off when lit. The glove box light switches on and off whether open or shut (can hear the clicking). All the dials started working intermittently and now have stopped working most the time. The warning lights on the instrument panel go on and off like a fairground. It gets worse when not accelerating. Engine runs fine apart from a momentary dip in power when idling with each flicker of all the lights.

 

What would cause this?

Are the earth points clean from the battery to the body and the engine block there one under the battery tray

Yeah, you have some damaged/corroded wiring somewhere or a damaged/corroded or loose earth point. Check every electrical connection and earth point first.