Upgrades to the West Coast mainline between London and Glasgow will fall far short of original plans.

Some £9.8 billion is to be spent on 780 miles of the London to Scotland route, with work set to be completed in 2008.

But Virgin's 125mph trains will be will be unable to run at the 140mph initially proposed.

The decision to scale back the modernisation came as the rail watchdog said the initial proposals did not deliver "value for money" to the taxpayer.

The much-delayed modernisation will cost up to £12.5 million a mile.