The feat of speed by the Bulleid Pacifics were not the only remarkable speed attempts. It was reported that a sports car driver travelling on the MI saw a steam train and attempted, as you do, to race it. He found that it was travelling in excess of 90 mph, and his passenger had a camera, and took a picture. When the picture was shown to a railway enthusiast the locomotive was not a Stanier Pacific nor a Britannia but a 2-10-0 . In fact it was one of the series originally fitted with a Crosti boiler!
The Western Region was eventually told to desist when a number of passenger runs were timed at excess of 90 mph with one of the 9Fs on the front. By all accounts they were remarkably free running.