LONDON (Bloomberg) Britain's first bullet trains entered service in London this week, bringing high-speed travel to the world's oldest rail network, but government spending cuts prompted by the global recession may stunt plans to extend the project.

The 225-kph trains, made in Japan by Hitachi Ltd., cut journey times by 50 percent from north Kent on the southeast coast to London's financial district using the High Speed 1 line built to carry Channel Tunnel services to Paris and Brussels.

U.K. Transport Secretary Andrew Adonis said the fast Hitachi trains will act as a catalyst for construction of a High Speed 2 route running north from London and slashing journey times to Birmingham, Manchester and other U.K. cities. Christian Wolmar, author of "Broken Rails," a history of Britain's railways, said he doubts the line will get built.