Reinstating the 11km line, which closed in 1969, would provide towns such as Oxted, Crowborough and Uckfield with a direct link to the south coast.

The most recent study into the project was carried out by Network Rail in 2008, with passenger demand and business case elements subcontracted to Mott MacDonald. This established that the benefit-cost ratio of a straightforward reinstatement of the railway would be between 0.70 and 0.78, well below the 2.0 minimum specified by the Department for Transport (DfT). The report found that the dominant rail market in both Lewes and Uckfield was peak commuter flows to and from London, and both towns are served by frequent services to the capital.

A change of trains at Lewes would also be required for passengers travelling from Uckfield and Crowborough to Brighton, which is likely to be the principal driver of demand for travel to the south.

Pressure group Brighton Main Line 2 (BML2) is calling for the line to be reopened as part of much wider project to increase capacity between London, Brighton, and the south coast, relieving the congested line through Redhill and Three Bridges. Under the BML2 proposals, the Croydon – Uckfield line would be upgraded, with electrification south of Uckfield and an additional link between the reopened section and the Lewes – Brighton line. This would be accompanied by the development of an alternative route between Croydon and the London area to avoid key bottlenecks and provide a more direct link between Sussex and the business districts of the City and Canary Wharf.

BML2 chairman project manager Mr Brian Hart argues that a new study will simply echo the conclusions of previous reviews. "Network Rail's 2008 study proved beyond doubt there was neither a business case, nor an answer to their capacity conundrum by opening a local line," he says. "Whilst we are all heartened that Patrick McLoughlin is "alive" to opening the line, this is not a local issue but a massive problem for London and the South East. It can't be done on a shoestring. Without BML2 the region will ultimately reach rail gridlock as this is the only realistic means of providing the capacity so badly needed."

Network Rail says it is already reviewing options for capacity enhancements on the Brighton Main Line and this work will feed into its Sussex route study next year. "The railway between London and Brighton is one of the busiest routes in the country and there is very little capacity for additional trains," says Mr Richard Eccles, Network Rail director of network strategy and planning. "As the number of passengers continues to grow, it is right that we look at a wide variety of options which may help to provide extra capacity in the future."