Saving Old Seagulls

102 plus standard shaft, low reduction box, fitted with the big barge pusher, 4 blade prop, long range tank, mark 1 ignition, long water jacket, chrome exhaust tube, rubber mounted brass tiller handle. I have had this 102 for some time sitting at the back of my workshop, it's in super condition and runs wonderfully, now the puzzle! It's number is AWCR3965, well I've looked in all my books and cannot find it listed! The crankcase is in super clean condition with no marks or scratches around the number and I have doubled checked this several times.
Any ideas on the year of this engine would be great.
Andy

Hmm - a proper mystery.

I have pondered what lists I have and can't come up with anything sensible. With that prop it has to be a clutch model, a Plus.

Mark 1 ignition and rubber mounted tiller mean fairly early. The R indicates reconditioned.

But I'm afraid it just doesn't add up!

Is the crankcase with the tiller arm lug the correct type? (ie not the later one with the 'half round' bracket?