Test there's power at the fuse first,fuseboxes are notorious on mk5 onwards escorts.if you've got a multimeter,dc volts,one probe on the metal exposed bit on the fuse,the other onto earth(any exposed metal on the car like the door catch).should be 12v both sides of the fuse.
Next,pull the bulb out of the holder and check for power there.
If that's all ok,but still no lights,set your meter to ohms or continuity (usually beeps when the circuit is complete) and test that the black wire (from memory) is going to earth,so one probe on earth,one on the black end and try again.
Alternatively,remove the all the bulbs,see if you get power,then replace them one by one and see if the lights suddenly dim.if so,you've got an earth issue.
I'm back in Swansea for the next few weeks if you get really stuck.I live down in pennard.