HS2 'vitally important for economic growth' The government has rejected calls from the former Business Secretary Lord Mandelson to rethink its high speed rail project. In the last week the cost of HS2 has risen by a further £10bn to £42.6bn and Lord Mandelson suggested it could prove an "expensive mistake." But Transport Secretary Patrick McLoughlin told the BBC's Richard Westcott that a lack of rail capacity meant the high speed network was needed.