Not fully sure but...
I think that he is now the late Eric Day... I am open to ridicule (normal day to day for me) if I am wrong but I think that he passed away a couple of years ago. One of my ex-sqns has a watercolour by him, but sadly we were too late to ask permission from him to make copies.I agree that his paintings captured that certain character of the aircraft. I would have liked a copy myself.