Gary. On the face of it it is a 1953 bike. The front mudguard has the centre rib, and is composed of three pressings, blade and two sides. Later versions are a single pressing. Prop stand with a brazed on frame lug first introduced in 1953.
Model year and date of manufacture are not the same, bikes produced in say September 1952 would be classed as the 1953 model year. This semi unit gearbox bolted to engine style continued long after the introduction of the swing arm frame. Steering lock was introduced 1955/56, early bikes don't have this.
The real conundrum is whether the machine is entirely original or composed of mix'n match parts. Engine and frame numbers do not match, but the engine units sometimes carry date stamps, inside the primary case by the tensioner is the usual place, sometimes near the pressure relief valve on the timing side.
The registration number back in the day has two letters to identify the area of registration, in this case VT, but to find when this number was allocated will take some effort.
J & N Basset, Howards Place, Shelton, Stoke on Trent Staffordshire were the dealers mentioned. So a mystery remains if two frames have the same number!
Swarfy.