This is the first of a series of short railfan videos that I took out of train windows while traveling from Cardiff to Prague. "Railfan" is an important qualifier here. I didn't expect any of these videos to be spectacular by themselves, Instead, they're aimed primarily (maybe only) at railfans who like to watch high-speed train videos. Technically, in modern terms, these Intercity 125 diesel trains, introduced in 1976, aren't high-speed in the modern sense. This is because their maximum legal speed is, and has always been, 125 m.p.h., or about 200 km/h, while the threshold for modern high-speed trains is about 210 km/h, set by the Japanese Series 0 bullet trains in 1966. However, the Series 0 bullet trains ran at 200 km/h from 1964 to 1966, and when the Intercity 125 diesel trains were being developed by British Railways in the 1970s, they were referred to as, literally, "High Speed Trains," or HSTs. Today, they're still often called HSTs, and remain some of the fastest diesel trains in the world, 39 years after being introduced to regular service.