I've been doing some research on this one to prevent a slow slide into the Black Hole. Photos of the exact car are available on a certain site, and I'm waiting for info back from the site owners. The puzzle photo and those I have seen show the car in a different form from what it looks like today, and I believe that the black-and-white pics go back to when the car was built as a special, probably the 50s or early 60s.
I have found other pictures of an Austin 7 special wearing the same registration taking part in the Cobham Trial 2010. It is described as an Austin 7 Ulster, and driven by a Graham Fullalove. It is painted orange, and the exhaust is routed under the car, but otherwise it looks very similar. I can only assume that it is based on an original Ulster, because it sure doesn't look like one. As and when I hear from my source, I will advise you. Meanwhile, does the above ring any bells?