Proposals for a super speed rail route from London to Scotland suitable for trains travelling at up to 186mph are to be unveiled by a Network Rail boss.
Deputy chief executive Ian Coucher is putting the ideas to a meeting of the Institute of Civil Engineers on Monday.
A new route would overcome bottlenecks in Herts and Northants and encourage competition with airlines, he claims.
Train services would only stop at major conurbations such as Milton Keynes, Northampton, Birmingham and Manchester.
The service would operate every 30 minutes and passengers could travel between London and Glasgow or Edinburgh in about three hours.
The cost of the line would be about £15bn but raising the finance would be the hardest job.
Mr Coucher is expected to argue that if the service attracted enough passenger traffic there would be no need for a public subsidy.