Missing Glove box light Fiesta MK8.5 Vignale How I fixed it

First I obtained the combined switch and light [image 1] as suggested by Stephen Ford (thanks for that)

Note the compatibility checker will say it won't fit your car, ignore that it will.

Next get a connector, in fact a standard 2 way molex [image 2]  will fit if you remove the lugs, but you will need a molex crimping tool (I have one) attach about a metre of wire as shown

The cover must be removed to get access to the switch position, this is held in by 2 screws just inside the top edge of the glove box image 4 , it is possible to get these out without dismantling any further but most screwdrivers will be too long.

So although you don't need to do this to get to the fuse box in a 'Facelift', you must drop the Glovebox fully down to get the lamp cover out. I am no longer strong enough to force the sides of the glovebox in  as suggested, so I used 2 pieces of wood about 8mm thick and 30cm long insert these into the gaps on either side of the glove box and lever inwards using not quite enough force to break the plastic.

The box will drop down as shown in  [image 5].

Now the main reason for dropping the box, there is a third bolt holding the assembly in place [image 6] this is right at the back of the assembly, impossible to see never mind remove with the glove box in place. Use an angled box spanner to remove it

The shelf assembly will now come free just a small clip holding it that will pop out 

The switch unit can now be clipped into position under the dash.

I ran the wires down the back straight to the internal fuse board, Negative with fastened to a bolt to the left of the fuse box, as shown in [image 7]  the cable bundle will push out of the way if you have one

I obtained a Micro 2 fuse tap from Amazon and fitted it in Fuse 18 (Labelled 24 on the moulding) this is listed as 'Spare' it's on with the ignition off. In fact I heard a small click when I pulled this fuse so its not unused, no idea what it does do though. 

If in doubt wire to the roof light, but you will need to dismantle more stuff.