Anyone know what the name of the anti-theft key system on the Ranger was?
Without the key inserted the vehicle would not start but the radio, lights etc still worked.
Any help would be much appreciated.

It's called a PATS system it stands for Passive Anti Theft System. If your vehicle is not starting, then you might make sure you only have one PATS key on the chain. The transievers in the column are bad about going out as well.