Welcome paul,,, just been thru this,, you date it off frame number, you"l need a cert [ paul dawkins] you"l not get original Number. but age related,
don"t do what i did,,, i had a number plate [ came with bike] tried to get V5 on this plate, had to go for inpection , turns out , frame was off one bike /engine from another , & plate from another, ,, almost resulted in a Q plate, no have to date it off frame, M.O.T. , then apply for classic made from different parts,