Foz - cali_passion has first dibs, so I will need to check with him if he is still interested in the ones pictured (if he wants these, I have a few other pairs which I will stick pics up - they are all vgc)
The covers fit by clamping the elastic clips between the rim and the galvanised steel ring. You have to remove and refit the spring steel clips to do this and these are a bit fiddly, especially at the deepest part of the rim (the outermost part when fitted to the van/bus). The fiddliness (is that a word?!) can easily be overcome with some long nosed pliers and some choice swearing
They don't quite cover the original glass lense fully - there is about a 5mm gap around the edge, but I reckon they look pretty good myself.