Unfortunately the building has been demolished - was a lovely big old house with horse and carriage place at side, steps up to front door and loads of land. I have been on Google street map and can see the houses\flats built in its place. Short of going back donkey's years to search for estate agent's details when land was sold to be developed, I don't think I have a chance really. I saw one post card on e bay and missed the end of the auction. It was only of Park Avenue in general and not the school but I would have liked it anyway.
Never mind - thanks for your interest.