The privatisation of British Rail was the process by which ownership and operation of the railways of Great Britain passed from government control into private hands. Begun in 1994, the process was largely completed by 1997. The deregulation of the industry was in part motivated by the enactment of EU Directive 91/440 in 1991, which aimed to create a more efficient railway network by creating greater competition.

The railway system in Great Britain is the oldest railway system in the world. The first locomotive-hauled public railway opened in 1825, which was followed by an era of rapid expansion. Most of the track is managed by Network Rail, which in 2017 had a network of 9,824 miles (15,811 km) of standard-gauge lines, of which 3,339 miles (5,374 km) were electrified. In addition, some cities have separate metro, light rail and tram systems, among them the historic London Underground and the Glasgow Subway. There are also many private railways, some of them narrow-gauge, which are primarily short lines for tourists. The main rail network is connected with that of continental Europe by the Channel Tunnel and High Speed 1, opened in 1994 and 2007 respectively.