Having put on a set of Lou's bumpers and overriders (these needed a bit of "fettling" to take the lamp plinths) I made up some stiff plastic spacers - invisible when fitted -to make the plinths seat properly - I then had to fit the lamps.
Remembering to put the thin nut and washer down the cable before fitting it to the reflector (no I didn't of course!) the next problem is how to tighten the nut to stop "spotlight droop". The nut cannot be accessed properly with an open end spanner, and it is unrealistic to tighten up before threading the cable in- the light won't point anywhere near where it is wanted!
So what to do? Buy the cheapest used 7/16W ring-spanner you can (£2.00 tops),cut it in half, cut out two segments from the ring and you have the perfect tool. It will slip over the cable, it is short enough to use in the confined space, and it is plenty strong enough to tighten the slim nut!
job done.