Here's a link to an interesting Moss Motoring article about Shelby and his connection to Donald Healey. I had frankly forgotten that CS had set several land speed records in Healeys. Per this article Shel initially contacted Donald Healey about his "V8 in a British roadster" idea, was turned down, and called AC. I believe I've read that before but it's been years since I've looked at Carroll's pre-Cobra history.
August 23 and 24, 1954 – Moss Motoring