One of the dangers of going ahead with the £18 billion plan to build a high speed rail route from London to Birmingham was that the existing rail network would be starved of investment, railway author Christian Wolmar warned MPs today (21 June 2011).

He said it was fanciful to think that we would get both.

Mr Wolmar was giving evidence to the House of Commons transport committee inquiry into the Government's high speed rail plan.

He conceded that it would probably have been better to build the high speed from London to Birmingham 15 years ago, before the West Coast main line was upgraded.

But it is absolutely critical to keep investing in the existing network, said Stephen Joseph, chief executive of the Campaign for Better Transport. He said that the French had made the mistake of neglecting their existing rail network in the early days of building their TGV lines.

He said one of the important rail projects that needed to be implemented was the East West rail link with Oxford-Cambridge as its core.

Mr Joseph also said that the French were adamant that parkway stations do not work on high speed lines.

"High speed trains need to serve city centres," he said.

Anthony Smith of the rail watchdog Passenger Focus said the quicker the high speed line was built the better for rail passengers and for economic reasons.

"2026 is a long time to wait for a train," he said. "but continued investment in the existing network is essential."

He added: "It would be a disaster, however, if the new line was perceived as a rich man's route and not accessible to ordinary people."

He said that Network Rail and Passenger Focus were investigating how the increased capacity on the existing network (released by the construction of the new line) could best be exploited.

Lord Berkeley, chairman of the Rail Freight Group, reminded MPs that both passenger and freight rail traffic is expected to double in the the next 20 years.

He also called for the high speed line to go ahead as quickly as possible and urged that there should be a link between the existing high speed line from Kent to London and the proposed line from London to Birmingham.

Network Rail's director of network planning Richard Eccles said the cost of a high speed line adjacent to the West Coast main line had been examined but he was unable to tell MPs what the cost was.

He said demand for more services on the WCML would become apparent within the next seven years.

Capacity was being improved by new ERTMS signalling, a power upgrade, grade separation at Stafford, remodelling at Bletchley and the Nuneaton new chord.

Nicholas Petrovic, chief executive of Eurostar, said the company had increased its market share every time the speed of the service had increased.

Rail had virtually none of the London-Paris market before the Channel Tunnel was built but now has 80% of it. Eurostar carried 9.5 million passengers last year.

The French TGV network now carried 120 million passengers a year, said Pierre Messulam, ERTMS director of SNCF.

Over its 30 year programme of high speed line building, SNCF had found that the actual growth was on average within 6% of its projections.

On the last two lines that were built, growth was far in excess of expectations.

He conceded that there had been some opposition to building the high speed lines, but asked whether people complained once the trains were running, he said: "Frankly speaking, no!"