I hope you didn't mangle the switch casing too much.
**For the benefit of the others who read this post you need to use a sharp modelling knife/razor to cut the two wires to the microsswitch and to dig-out the moisture proofing wax/rubber gel that covers the switch soldering points and around the edges. You need to cut the wires to get the switch out of the casing, as the switch clips intoplace, which is possibly why Andy had to mangle his casing.**
Anyway, Andy, the microswitch you need from Maplins is this: http://www.maplin.co.uk/Module.aspx?ModuleNo=34835
The model number/code is: N96AQ / Min M-Sw with Lever.It's the one with the metal strip (but without the roller at the end of it). The microswitch is actually slightly thicker than the original Ford one, so you will need to usea bit of force to push the switch into the casing. However, you shouldn't break the switch casing in the process, as it's quite flexible.
Once in place you will also need to bend the tip of the microswitch metal lever upwards, otherwise it wont make contact to the mechanical switch housing. It's a trial and error process, but I found that bending it about 4mm upwards at the tip should do the trick. I suggest using your left thunb to hold the end of the strip that enters the switch itself and at the same time use a finger on your right hand to bend the tip upwards. If you do this you reduce the risk of breaking your shiny new microswitch.
Once you have soldered your wires back onto the new microswitch and tested it, then use mastic/bathroom sealant from a DIY shop to seal the exposed soldering points. This is important, becausemoisture is generally the reasonwhy the microswitches fail in the first place.
Finally, once you have the microswitch in place -and before you bolt the tailgate number plate lights strip back into place -I strongly recommend using some bathroom sealant over the almost certain damage to the existing seal caused when unbolting the number plate light strip to get to the microswitch. Again, if you don't do this, rain water will seap into the broken seal around the numberplate lights strip, and even worst water will drop onto the boot door alarm switch and key barrel. The result of this will be your car alarm will continuously go off, and the barrel will corrode. Both of these can't be fixed without going back to Ford.
With all that said, don't be put off by the above. It really is a relatively simple job, so long as you take care.