Nice picture taken in the year I was born!
It seems to be a bit of a mix of early and later type Nortons.
The oil tank is definitly late but the rear carriers and toolbox are early.
Do you know a little more about what happened with it?
As mum was fed up with it he did a straight swap with a Morgan with a matchless v twin, he then sold that for £30 he enjoyed telling me that when I was in my twenties. Here is a picture of another one of his bikes, so looks like he made them up. Is there any way of finding any history of the combination by the number plate ?