Help with serial number for 615 squadron hurricane in December 1940

Dear all,

I am trying to locate the serial number for a hurricane flown by Jocelyn Millard in December 1940.
The hurricane in question was flown by him on December 17th and according to his log book was KW-J.

On this date he patrolled the Maidstone line at 10,000 feet.

I am having a model made for me which I would like to be accurate.

Many thanks in advance for any assistance that you may be able to offer me.

Regards

Gerry