Liberal Democrat leader Nick Clegg has unveiled plans for a string of garden cities along a new railway link through the "brain-belt of Britain".
Stations along the express route from Oxford to Cambridge would be granted to up to five towns that agree to build between 9,000 and 15,000 homes, the Deputy Prime Minister said.
The first section of the line is already going ahead but the Bedford to Cambridge stretch, estimated to cost up to £1 billion, will start only once the deficit has been cleared.
Answering questions from activists at the Liberal Democrat conference in Glasgow, Mr Clegg said: "Garden cities are something I have been banging on about for years and Conservatives have been resisting for years.
"We are finally making some progress. I announced this morning that we want to see the completion of the Cambridge to Oxford railway line, because that railway line is in part of the country where we think a lot of the new garden cities need to be established.
"We think that at least three major garden cities should be constructed on that route - tens of thousands of new houses, but crucially homes built in a properly-planned sustainable way."