Great Britain, with a rail network disadvantaged by half a century of underinvestment, is about to introduce high speed trains. A first project, using tilting trains on the major rail link of the country between London, Manchester and Glasgow, is based on a deep modernisation of the existing infrastructures. The other project consists in building a new line between London and the Channel tunnel, that extends the European high speed rail network. Nevertheless, these improvements were not obtained through exclusive private funds as the government expected it in privatising the rail system, and the slow modernisation occurs with heavy public subsidies. From a spatial point of view, the new high speed rail line, introducing new connexions at the national and international but also regional scales, contributes to a recomposition of the Great Britain's rail geography.