No, the old wheel doesn't have a plate either, it had the standard seal forced into the retainer - that's what caused my initial confusion.
I've ordered a seal that should fit into the retainer, with the collar reversed just to ensure the seal doesn't work it's way out I'll then have the same additional sealing for the bearings as standard. It will mean that I wont have the plate and O-ring keeping dirt out off the retainer, I'm thinking of just coating it in waxoil.
I think this should be OK long term, but I'll still keep an eye out for a plate turning up at a reasonable price.
I'm looking to get it back on the road fairly quickly so I can do the little jobs my vfr needs without having to rush them.
Cheers
Allan