Concerns about the Waverley line have been voiced in Holyrood

However, the new government has said that timescale is not achievable and has expressed concern about the funding package behind the scheme.

Councils along the route have said that they have no more money left to invest in the project.

It has left a string of questions which the BBC Scotland news website put to a Scottish Executive spokesman.

Q: Exactly how much is the "funding gap" which has emerged in the project?

A: Anticipated final costs and timescales will be established once Transport Scotland's due diligence review has been completed.

Q: Why does the government feel the onus is on the councils to fill that gap?

A: Ministers stated their commitment to the project in parliament, saying they would honour the previous government's contribution of �115m (in 2002 prices), however they also expect the councils and developers to meet any funding shortfall.

Further conditions are that the assumptions of the business case continue to hold, a clear and comprehensive risk management strategy must be developed and delivered and the railway must be efficiently integrated with local bus services.

Q: Transport Minister Stewart Stevenson said the target date of 2011 was "not achievable". On what date does he believe the Waverley line will reopen?

A: I refer you to the first answer above.

Q: Is there a real risk that the line will not reopen at all?

A: I refer you to the second answer above.

Q: Why have these concerns only come to light now after MSPs voted almost unanimously in favour of the plans?