Chris, thanks for stopping by. On another fan site the shape of the roof reminded me of a roof-less parade car which was going to the UK to become an Ecto… it's great to see the finished result.
Having met Milton, and had the pleasure of participating on at least two tours of duty with his Car, it's great to hear he was involved with that one.
I'll pass along your post to the folks on the U.K. Ghostbusters forum, the guys there are extremely keen to know more about the “Leceister Square Ecto”.