This afternoon I felt guilty because I couldn't get motivated....and finally the rush of energy came at about 11pm. So I got togged up against the cold, went down to the shed and beavered away, getting the wheel backplates off the rear axle, then came indoors, spread newspaper over the box-room floor, opened window and front door for ventilation and sprayed (front axle) backplates and all four brake drums with high temperature paint. This may be over-kill, but as the drums are going to get hot, it just seemed sensible.
The picture shows the second coat. As you can see, it is cloudy matt in appearance, but bear in mind that it won't be visible: wheels are mounted on the drums and the backplates are going to be beneath the horizon and in-board. Incidentally, thinners were used to de-grease the parts before the primer coat was layed down (no primer needed) and the studs were taped to stop paint gunking up the threads.