I was driving home tonight,flicked the lights on.And there was a small fire under the dash.Any ideas.

Have you replaced the headlight lamps lately? Putting 100w ones in by mistake, coupled with wrong size fuse will cook your wires

Could also be a loose connection or 'hot joint' in the wiring causing high resistance/ melted cables and components. 
 

But the strange part is, it never blew a fuse.

smallvan
But the strange part is, it never blew a fuse.

If all your fuses are the correct current rating then I would guess high resistance connections with wiring/ components. Which section of the loom caught alight?
 

Dimmer resistor caught alight?  very common....
 
Cheers

Seems all to familiar with old escort wiring, particularly when others have messed around with it in the past. My best advice is a power isolation switch that you can access in the car. An extinguisher is a handy tool too. Some might say overkill, and if your wiring is in good unmolested condition it's probably not needed, but you'd be amazed at how quickly a fire can take hold.
Shaun.

this may have been creeping up for some time, oxidised connectors would cause high resistance,
cooking your wiring, you need to replace damaged wire from it's origin, to where damage ends, 
also new connectors, me thinks.!!

Sorry to hear about the electrical drama, really can't help with a diagnosis. I'm with escortinadriver though, an electrical cut off is good insurance, I've mounted a 'ripcord' under the seat just in case.....
Good luck with it Drew............

This is what caught alight