ALEX Salmond's image as a staunch champion of Scotland may be damaging his chances of winning the independence referendum, polling experts have suggested.

The Scottish Centre for Social Research (ScotCen) has highlighted figures showing that since the SNP came to power and Mr Salmond became First Minister in 2007, more people now feel Scotland gets a good deal from being in the UK.

As First Minister, Mr Salmond has taken a confrontational approach to dealings with Westminster, rarely shying from a fight with the UK Government.

The ScotCen report, co-authored by Professor John Curtice of Strathclyde University, said: "One of the most striking findings of the Scottish Social Attitudes survey in recent years has been that Scots have appeared rather happier with the deal they get out of the Union since the SNP first came to power in 2007.

"Scots also appear to have taken a more positive view of the achievements of devolution since the SNP came to power."

The latest Scottish Social Attitudes survey, conducted between July and November last year and published on Wednesday, showed support for independence has fallen to 23%, the lowest level since devolution.

The number feeling "confident" about an independent Scotland's prospects was 21% (down from 31%) compared with 59% who were "worried" (up from 46%).

But more detailed statistics released yesterday raised the possibility Mr Salmond has become a victim of his own success in projecting himself as a champion of Scotland's interests.

The figures showed 28% of voters believed England did better economically from being in the UK, a slight fall from the previous year, compared with 67% who felt the deal was fair or favoured Scotland.

Under the SNP, the number of those unhappy with the deal has been consistently lower than under previous Labour-LibDem administrations.

From 1999 to 2006, it ranged from 30% to 42% but has fallen to between 23% and 29% since the Nationalists won power. Scots also felt Holyrood has given them a stronger voice in the world since the SNP took control.

Separate findings showed trust in the Scottish Government remained high, with 62% of voters saying it worked in Scotland's best interests, though the figure was down from 71% the previous year.

In a presentation to academics and campaigners, Mr Curtice suggested the Yes campaign's task had been "made more difficult by changed views of the economics of the Union since 2007".

One of the main conclusions from the latest survey, which has been conducted annually since 1999, was that the economy has become "by far" the most important issue in deciding the independence referendum.

The pollsters found confidence about a go-it-alone Scotland's prospects was more closely linked to economic expectations than feelings of national identity.

Of those who see themselves as "Scottish not British" – the group with the strongest feelings of national identity – fewer than half (46%) wanted to leave Britain. The figure has fallen from 53% compared with the previous year.

New survey data also showed women are still significantly less likely to back independence. Twenty per cent of women supported leaving the UK, down from 29% the previous year while 29% of men backed the split, down from 36%.

Much of the survey was conducted before Deputy First Minister Nicola Sturgeon was handed a high-profile role as minister for the refrendum.

A Yes Scotland spokeswoman said: "As it becomes clearer that only independence can deliver a fairer and more caring Scotland, we are confident many more voters, including women, will vote Yes."