There was a recent question re "Why no light/ lamp over the engine?"
I have looked in my old Ford Mondeo "useful info" file.

I seem to recall the part is for a Ford Probe which were made in the USA and a few sold in the UK.

This is old information ( 2004) but may still be correct.
Ford part numbers are
Loom 94 BG-15A702 BBG
Light unit 93 BG-15702 AC

This info may be useful for someone who wishes to persue this modification. I have no info re fitting but certainly it was simple on the Mondeo.

I have now found the original web item with pictures.
Fitted the ford genuine engine compartment light - Electrical (Mk3 Mondeo) - TalkFord.com

I am getting some possible hits when searching on Google for the part numbers- Maybe also a Mustang part

 

I use a magnetic LED Torch/Flashlight that I keep in the Trunk/Boot. It works great on steel (X-Type)but worthless on the aluminum X350.

It looks similar to this:

 

That is exactly the style of torch that lives in the strap by one of my rear lights.
I have another magnetic orange flashing beacon installed above my umbrella straps.
Similarly my beacon does not like the trunk/boot liner between it and the steel. I had to drill and insert a self tap screw with a big washer (under its head ) so now the magnet works very well.