I've used this morning to contact another member who has better knowledge of this era of racing, and his reply has been very helpful. By sheer coincidence there is a thread running on another well-known website concerning this very sporting event, which is, as you correctly say, Prescott in 1947. Using information from that site, and then my own reference books, I've found out what it is!
The "Bellamy" suspension is in fact an Andre-Girling set-up. The car is a Riley special built by Percy Maclure pre-WW2 (commonly known as the IFS Riley Special) into which he fitted a 1488cc supercharged ERA engine. At this event it was entered by S B Reece and driven by Sheila Darbishire. The numbers on the side of the car don't fit the programme details, but it was common in those days for 2 drivers to share a car at one event, and possibly the numbers were changed in between runs up the hill.
In 1948 the car was purchased by Geoff Richardson and he began a series of modifications which resulted in it becoming the RRA, which we've had as a previous puzzle.
Sorry for the delay - I think you've done enough to win the point. (Doug McLure was a well-known American actor in Westerns).
