I have not fitted them in cars, but you can either wire them from a cabin light that operates when door is opened, which is quite a bit of work, considering you have to get behind roof level light trim, and get inside door cards. Or.....
The easiest and cheapest option is to fit magnetic switch operated puddle lights that use AAA or AA batteries.
You just make sure you order them with the FORD logo. No wiring needed.
There are many makes and types out there (ebay, wish, etc), some better looking than others and project the logo better and brighter, price range seems to be from £6 up to £20 for the pair (for 2 doors). You fix the puddle light to the door card, and line up a stick on magnet strip on the car frame below the door with the puddle light. Operation: when you open the door the puddle light moves away from the magnetic strip, and a magnetic switch inside the puddle light switches on the light. It goes off when you close the door.
Downside, trying to line up magnetic strip takes time and effort. Keeping puddle light stuck to door card can be difficult, may have to resort to two part epoxy glue rather than the stick-on tape supplied. Having to replace the batteries every so often.
Thank for that Colin, that's does sound easier. Have spoken to someone who did put them on the underside of the door mirrors on a fiesta of the same year. The near side was not to bad as the fuse box was that side, the offside was a great deal more work.