my local bike mechanic just happened to have an Africa twin engine completely stripped down, so was able to check out where the engine size is stamped. It is on the forward facing cylinder, facing forward directly under the water inlet.
So off I go this arvo to the shop where the A.T. is on show, to check engine size etc. When I got there, alas no A.T. The shop has sold the bike, for 250,000 baht - so now we will never know. This price will obviously make the owner selling happy, as he had paid 280,000 baht for bike last year.
Thanks everyone for all your input, didn;t realise the amount of interest the bike generated, and was interesting to read how some of you were so definite about the model/year, even though there was a large variation between years.