Pre-1960 slimlines

Is it true that some MY(Model Year) 1960 slimline Dominators were produced in calender year 1959?

Based on factory operation for many decades prior and since then for Norton and most all other Marques in the world, the answer (only a guess) is yes.

Some one with access to factory records or internal factory history would need to address preproduction prototypes and if any pre-1960 slimline therefore MY 1959 production were built.

My 99DL was the 86th built in late 1959.

My Slimline 99 DL was registered on 15 Dec 1959. The head steady bracket stamp dates it to October 1959.

My slimline M50 was first reg on 12 Oct 1960!, in Braintree Essex.

I thought dommies were produced a year or two before in the slimline frame.

Regards John O