The company that manufactures Class 43, also known as Intercity
125, is BREL Crewe Works.
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It is - 225 relates to the kmh of the top speed. In the UK, the
Intercity 125 is more commonly known as an HST (High Speed
Train).
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The Intercity 125 operates at a speed of 125 mph in regular
service, and has an maximum speed of 148 mph making it the fastest
diesel-powered train in the world, a record it has held from
introduction to this present day.
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125mph, hence why the class was also called the intercity
125