The vow of enhanced Home Rule swayed votes in the referendum, but not by as much as has been claimed, according to research by the Future of the UK and Scotland project.

Professor Ailsa Henderson of Edinburgh University told a joint conference with the Scottish Centre on Constitutional Change that 60 per cent of No voters believed new powers were coming to Holyrood, in contrast to only 10 per cent of Yes voters, but a rolling survey over the final weeks of the campaign revealed a more complex picture.

"Was the vow influential?" she asked. "It is true that the belief in more powers rose, but only slightly over the series."

Other factors were just as significant, with clear evidence that the fears about economic consequences of independence lessons lessened, while the arguments from the pro-independence side that a Yes vote would help create a more equal society strengthened.

Professor Henderson said this indicated that another week of campaigning could have made the result closer.

She also revealed a breakdown of sampling far greater than any opinion polls which showed that the new voters enfranchised at 16 and 17 actually voted against independence by 52 to 48, while their elder brothers and sisters up to the age of 24 voted against by 51 to 49. It was those aged 25-29 who emerged as the most enthusiastic Yes voters, by 60-40.

Professor Charlie Jeffrey of Edinburgh University spoke of a chain reaction set in motion by the late YouGov poll showing a lead for Yes late in the campaign, the sudden pledge announced by George Osborne, Gordon Brown and then the Scottish and UK pro-Union party leaders, and the abrupt shift on September 19 to David Cameron's emphasis on English Votes for English Laws.

"This chain reaction opens up a new terrain," said Professor Jeffrey, citing multiple conflicts between nations - England and Scotland over voting, Wales and Scotland over Barnett - and between Conservatives and Labour.

He added: "Labour is not finding the terms of victory to be very good, with Gordon Brown's freelancing unlikely to be welcomed by Labour in England, and the costs of non-delivery in Scotland huge. This chain reaction is unplanned, unstable and unpredictable."

He also claimed the timetable for the Smith Commission coming up with a new devolved settlement was "too tight for well-founded legislation."

Former First Minister Henry McLeish strayed from chairing the conference to add his own view that the timescale was "absolutely ludicrous".

He added: "If Lord Smith is serious about carrying on the legacy of September 18 he must engage civic Scotland and on this ludicrous timescale that cannot happen."