I forgot to say - I found a chassis number stamped into the bulkhead
Previously I had been lead to believe that Volvo didnīt start doing this until later 1966 (information found in a spares book)
However - my 1961 PV does have it
The chassis number plate is as many have said on the RHS of the vehicle (left hand arrow in the picture) - But this can be removed (!)
I found the chassis number and the model number stamped into the bulkhead between the hole for the heater ducting and the hole for the wiring loom on the LHS of the vehicle (right hand arrow in the picture)