One wonders if they purposefully picked days that had rain in the forecast for that episode... It seems like, a lot of the time, the destruction and so forth is just something they know they have to put in, so they do so. I mean, yeah, they have fun with it but it's so over-the-top and predictable these days.
In this case -
http://en.wikipedia....orth#Authenticity
Authenticity[edit]
For various reasons, it was not possible to run a historically accurate recreation of how the race would have gone in 1949. Instead, according to Graeme Bunker, the race was "done just for fun and entertainment".[6] A major restriction was Tornado's maximum speed limit of 75 miles per hour (121 km/h), set as a condition of its current main line certification (although the A1 Trust was planning to have Tornado certified to a higher speed over time). The 'Flyers' of the 1950s would have gone on to speeds of 90 miles per hour (140 km/h) and beyond.[2] A further difficulty was due to water troughs having been removed from the rail network, meaning it was not possible to achieve the post war steam timings of 6 and a half hours.[6] According to Steam Railway magazine, if Tornado had been able to use troughs, the train would have won the race easily.[2] On the plus side for the car and bike, they had the speed advantage of not having to travel through towns and villages exactly as the old Great North Road would have, but instead benefitted from the use of modern bypasses, and the faster A1(M) sections of the A1, where it has been upgraded to motorway standards.[6] However, speed restrictions outside of built up areas were only introduced in Britain in 1965. So if this had been in 1949 neither the car or motorbike would have been subject to any speed restrictions for most of the journey.[citation needed]
The best thing about Top Gear is the cinematography, IMO. The rest is meh, depending on my mood.
Here's a nice page on a '55 Black Shadow -
http://www.mctrader....icleid/85888.aspx
VincentÂs countless racing and speed record successes underlined the performance of its high-cam, 50-degree V-twin. In fact, attempts to run a 1000cc ClubmanÂs TT in the Isle of Man foundered after just three races because nothing could touch the Vincents  in the final 1950 edition, only Vincents took part. Nothing else could compete with these bike created by legendary Australian engineer, Phil Irving.
Cheers,
Scott.