SO who got the better of yesterday's historic agreement?

In one sense the answer can only be the SNP.

Alex Salmond has secured the right to hold a legally watertight referendum on whether Scotland should leave the UK and an understanding that the UK Government will respect the outcome should Scotland decide to vote.

The SNP finally has a chance to deliver the independence of which it has long dreamed.

Moreover, along the way, Mr Salmond has had to make remarkably few concessions on the issues on which the two governments were divided.

He will be allowed to give 16 and 17-year-olds the vote, so long as he can overcome the potentially not inconsiderable bureaucratic hurdles that lie in the path of so doing.

He has secured the final say over how much money each side will be able to spend in the campaign – an issue that concerned the SNP because a high spending limit would mean the Yes camp being significantly outspent by the wide variety of unionist forces ranged against it.

True, the wording of the referendum will not be entirely in the First Minister's hands.

He will be under heavy pressure to follow whatever recommendation eventually emanates from the Electoral Commission – but the question the Commission road tests will be the one that, after further consultation, Mr Salmond asks them to.

However, Mr Salmond has bowed to the will of the UK Government on what potentially was the biggest source of division between the two governments – what is to appear on the ballot paper.

There is to be only one question, with no vote on whether Scots would like devo max.

Ensuring a single question ballot seems to have been the one and only objective the UK Government had in negotiating the agreement. However, the SNP itself always said that it only really wanted one question.

So in the end it probably was not too hard for Mr Salmond to concede the point. He is taking the risk that he may come away on referendum day with nothing.

But equally, the UK Government is trusting that those one in three Scots whose first preference would be a lot more devolution continue to stick with the Union now that their preferred option is not on the ballot paper.

In two years' time we will discover which side has made the right judgment call.

l John Curtice is professor of politics at Strathclyde University, Glasgow.