interesting first few minutes of the series which set during the early 1950s. Nice to see some old cars being given the beans.
In the days before the timing was done using 'timing lights' at the start (and finish), cars used run a front tyre over and electrical trigger (looked a bit like a small pad/strip) which was quickly removed by the start line crew so the rear wheel (possibly spinning) didn't connect with it.
In the episode it looks like the GN (V twin silver car) and red Napier Lion engined car (the lady driver was later leaning against it) both did more than one practice run.....
Trouble with doing period filming, is all the background stuff that came along years later - The Armco barrier shown near the start was patented in '65, and the blue-and-white plastic covered foam barriers are way newer.
If you want to see old motors (similar to the episode) tackling the infamous hill, 6th July 2014 seems the time to visit Shelsley as the VSCC (Vintage Sports Car Club) folk will firing up some historic machinery.
http://www.shelsley-walsh.co.uk/events/content.asp?ms=21&ei=223