Thanks rudekid, I tried the guild of aviation artists a few weeks back. No dice I'm afraid. Although he was a member, it seems that the site admin bod had had no correspondance with Eric in many years.
It seems like sadly, the first couple of replies might prove to be bang on the money. There goes that commission I think, looks like I was too late.
One of life's regrets then maybe.....
Thanks for the replies gents.