The British Rail Class 303 electric multiple units, also known as Blue Train units, were introduced in 1960 for the electrification of the North Clyde and the Cathcart Circle lines in Strathclyde.

In the UK, the "Blue Train" typically refers to the iconic Blue Pullman, a luxury high-speed diesel-electric multiple unit that operated in the 1960s and early 70s. It was famous for its distinctive Nanking Blue livery and its "all-first-class" service, offering premium dining and speed between London and cities like Manchester and Birmingham. In 2026, the legacy lives on through the Midland Pullman, a restored high-speed train set that replicates the original blue aesthetic and luxury dining experience for special "rail railtours" across the British countryside. Alternatively, some commuters might associate the "blue train" with the Caledonian Sleeper, which features a dark blue livery on its modern Mark 5 carriages, transporting passengers overnight between London Euston and the Scottish Highlands. Both representations capture a sense of British rail nostalgia and premium travel, contrasting with the standard red, white, or green liveries of the modern privatized "Train Operating Companies" that dominate the standard network today.