More passengers are now travelling by train than at any time since 1946. Passenger numbers on Britain's rail network are growing faster than in any other European country - and, despite overcrowding, sharply rising fares and saturation on many main lines, there seems little sign of any slowdown in that growth. Network Rail yesterday published a long-term business plan that promised to increase capacity by extending platforms and adding more than 100,000 extra seats a day, doubling spending levels on expansion schemes, undertaking infrastructure projects such as the rebuilding of Reading and Birmingham stations, and expanding cross-London services. Ruth Kelly, the Transport Secretary, suggested that these plans would boost passenger capacity by 22 per cent. But it is clear that the Government is underestimating future passenger growth and the need to expand the network. The time has come to commit the country to more than cosmetic improvements and to start planning much needed high-speed lines.

In the past couple of years Network Rail has done reasonably well in overcoming the long aftermath of the Hatfield crash, clearing the maintenance backlog, improving punctuality and controlling costs. But these overdue reforms have underlined the soaring demand in an industry only now addressing the problems of expansion rather than contraction. Network Rail's admission that more than 100,000 passengers in the South East have to stand each morning give statistical backing to the vocal complaints by commuters of unacceptable overcrowding and rising anger at the tardy response.

Network Rail in its politic way is implying that Whitehall is, purposefully or otherwise, under-estimating demand. The Department for Transport forecasts a growth of 25 per cent until 2014, but experts note that this is an implausibly, even ludicrously, low figure. Little consideration has been given to the need for rail companies to boost their business, the predictions of rapid population growth, congestion charging and the reduction of car and aircraft emissions. Network Rail, a quasi-nationalised company, has to tread carefully in contradicting the Government. But unless urgent steps are taken to accommodate the train operators' more realistic estimate of 40 per cent growth, the railways will soon be gridlocked to the frustration not only of individual passengers but the business community collectively.

The Government must embark on a programme of major enhancements. A flyover here or a connecting chord there may ease a few bottlenecks, but this is nowhere near enough.

A new East-West freight route is urgently required. Many bridges must be rebuilt and gauges enhanced to accommodate far larger containers. Above all, a start must be made on a high-speed North-South trunk route to relieve the East and West Coast main lines, already almost at capacity. Private money is available with the right incentives, a stable planning framework and political will. It is a costly, long-term project - but Britain is already lagging behind its neighbours on the Continent. Gordon Brown, as a Scot, should know the value of providing the infrastructure to balance the pull of the South East. Rail ticks all Labour's political boxes - environment, pollution, congestion, regional development. It is time to build a new route for the Flying Scotsman.