My 55 plunger a10 gf has a deep square type front mudguard, I think that's the correct type for the year etc. The registration number is on each side of the guard in white stick on letters which was the norm then but did any ever have the stand up reg plate on top of the guard like later models did ? I have looked at many pictures of a10 plungers and not yet seen one .
Reason I ask is last week I saw at my local bike caf? a beautiful a7 with same square type mudguard and owner had reg plate on top and it looked a neat tidy job . Dave.