Railtrack's descent into administration four years ago was "triggered" by the government, reports today's Telegraph.

The paper says that documents, including emails, exchanged between officials and advisers at the Treasury, the Department for Transport and the Downing Street policy unit, speak of "engineering" Railtrack's insolvency.

According to the report, one email said Stephen Byers, the then transport secretary, was "very attracted to the option of pushing them [Railtrack] into administration".