This is Boo's 1939 Model ES2 Norton. Boo:
"This ES2 was offered in 1939: the plunger frame was a left-over from the earlier models and at a cost of £7-10 shillings was available for the camshaft- and ES2 models. The Inter type tank, with right hand filler cap and no pie crust was a pricely 30 shillings. These details are in the Works Records; it's not a Bitza, it left the factory like this."