The Liberal Democrats have pledged to complete the line Cambridge to Oxford in a move they say would dramatically cut journey times, if they win power.

Nick Clegg will say today that the move, which Lib Dem sources acknowledge could take a decade to be realised, would allow 50,000 new homes in 'garden cities' to be built.

Under the plans, the party will encourage the towns along the route to come forward with plans for housing developments of 9,000 to 15,000 homes, or more, and in return they will become so-called 'express stations' with higher frequency rail services.

Bedford, which is already planned to have a station on the line with work due to begin in the next rail spending period, has recently given planning permission for 18,000 additional homes.

Mr Clegg said: 'Britain faces a housing crisis. Every day, 200 fewer families own their own home, as home owners die and more young families get stuck renting, unable to afford to buy. Garden cities are a vital cornerstone of our plan to boost house building to 300,000 homes a year – enough to meet demand and keep prices in reach – while still protecting our precious green space and preventing urban sprawl.'

The Lib Dems claim the new line could cut journey times between Oxford and Cambridge from two-and-a-half hours to around an hour.