Tom Symonds BBC Transport Correspondent

The rail regulator is an uncompromising figure in the rail industry - Tom Winsor has never shown much desire to be popular.

He tends to avoid sound bites in favour of legal exposition and he's often been bluntly critical of the way the UK's railway network is managed.

Now he believes that while the drive to improve train punctuality has to continue at full speed, it must also be accompanied by an efficiency drive.

This is the essence of Tom Winsor's job.

Nothing's simple when it comes to the way our railways are run, but put simply, he has to ensure we get value for money from Network Rail, the company that took over from Railtrack.

Rail regulator Tom Winsor can be "brutally critical"

Mr Winsor sets the charges that Network Rail imposes on train companies for using the track.

Since these track access charges are Network Rail's main source of income, the Regulator effectively decides how much the company gets to spend.

Railtrack was spending slightly more than �3 billion a year on track replacement and signal repairs. Network Rail wants to spend around �6 billion.

But Mr Winsor's announced he wants that reduced to �5 billion and eventually �4 billion within the next five years.

But it is the effect of Network Rail scaling back its investment programme that is most worrying train companies.

Mr Winsor wants the huge project to revamp the main London to Glasgow line put on hold - for up to a year - at the end of 2004.

He believes that Network Rail, which is managing the scheme, does not yet have control over the amount of money it pays to the maintenance companies actually doing the work.

'Dynamite' proposal

The worry is that contractors ask for - and often get - lucrative contracts for this sort of job.

Mr Winsor wants Network Rail to stop work, renegotiate, and save a billion pounds.

The delay would hold up work on the line, much of it north of Liverpool which would allow trains to run to Scotland at 125 miles an hour, cutting 45 minutes off the London to Glasgow journey time.

It would also further delay future plans to increase the speed of the line to 140 miles an hour, making better use of Virgin's new tilting Pendolino trains, which are designed to travel at that speed.

As one source in the Regulator's office put it, this proposal is "dynamite."

Don't imagine for a moment that the train companies will pick up the bill for higher track charges

The problem is that last year the government's Strategic Rail Authority carefully renegotiated the work on the West Coast line, to cut costs.

The plan has just been finalised - including plenty of improvements after 2004.

Senior figures at the authority are talking tough - they're prepared to face up to the regulator, to push ahead with the West Coast scheme whatever he says.

It could escalate into a showdown between the rail industry's two architects - the bullish regulator Tom Winsor, and his younger counterpart at the SRA, Richard Bowker.

Virgin Trains is horrified by the Regulator's recommendation.

Chris Green, the Virgin Trains Chief Executive said "We're very angry, and Richard Branson is super angry".

Yet again the company's promises of a revolution in train travel are being undermined by delays.

Fewer services?

Network Rail is being careful to work with Mr Winsor rather than against him. The company's already vowed to cut a billion pounds from its programme every year, and work to improve efficiency.

Even though cuts are coming, Network Rail will still be allowed to spend more money than Railtrack did.

But do not imagine for a moment that the train companies will pick up the bill for higher track charges.

They are protected by the contracts that have for running their services.

Instead the government will have to pay - which means the tax payer.

And if the efficiency drive does not work, and the government will not pay?

Well then there will be difficult choices to make. Either fewer services will be run, lines will be closed, or fares will go up.