ALEX Salmond will tomorrow appeal to voters' sense of history in an attempt to overcome the No campaign's narrow lead in the polls as the referendum enters its final month.

On a visit to Arbroath, origin of the nation's most famous document, the First Minister will deliver his own "Declaration of Opportunity".

He will say a Yes vote on September 18 offers three key opportunities closed off by the Union: the opportunity to protect the NHS "forever" from Westminster cuts and privatisation; the opportunity to create a fairer society; and opportunity for more young people to find the job they want and stay in Scotland.

The last stop of the Scottish Cabinet's tour ahead of the referendum, the symbolic location is intended to evoke the Declaration of Arbroath, the 1320 assertion of Scottish independence from England which was the template for the American Declaration of Independence.

Hoping its inspirational message will rub off on the Yes campaign, Salmond will say: "A Yes vote on September 18 is the opportunity of a lifetime to build a more prosperous and fairer Scotland. Those of us lucky enough to cast our votes on that day are truly a privileged generation: perhaps the most privileged in this nation's history.

"We have the chance to take power out of the hands of the Westminster elite and into the hands of the people of Scotland."

The No campaign last night said Scots should not vote on the basis of "emotional spasms". Although Scotland is a wealthy nation, blessed with natural resources, Salmond will say that far too many people do not feel the benefits.

"We need to ensure that as well as being a wealthy nation, we also become a fair society. So today, here in Arbroath, I am setting out a Declaration of Opportunity.

"A declaration based on the potential of the talented people of this country that independence can release.

"One which sets out three key opportunities from independence: the opportunity to protect our publicly owned, publicly run NHS forever from Westminster privatisation and cuts; the opportunity to create a fairer Scotland, ending the assault on the most vulnerable members of our society, and the unfairness which has seen a huge rise in the use of food banks in a land of plenty; the opportunity for young people to stay in Scotland, to choose to build their future here because an independent Scotland has a strong economy, a just society and a good quality of life for all. It is because of these opportunities that we'll be better off with Scotland's future in Scotland's hands."

The Declaration of Arbroath, a letter written in Latin to Pope John XXII by a group of Scottish noblemen, is regarded as the founding text of the Scottish nation, and was revolutionary in setting the will of the people above the King.

Its most famous lines run: "For as long as but a hundred of us remain alive, never will we on any conditions be brought under English rule. It is in truth not for glory, nor riches, nor honours that we are fighting, but for freedom - for that alone, which no honest man gives up but with life itself."

Better Together chair Alistair Darling said voters need to look at the hard economic facts.

Speaking in Coatbridge yesterday, the former Labour Chancellor said: "The predictions of a Salmond surge remain unfulfilled. The milestones which were supposed to generate a tide of emotional support for breaking up Britain have come and gone. The Scottish nation knows this is too big a decision to be decided by emotional spasms."

The first campaign broadcast by Better Together will air tomorrow on both BBC and STV, the first of four such broadcasts by each side.

It will feature "patriotic Scots from across the country setting out why they will be saying No Thanks to separation on 18 September".

Better Together campaign director Blair McDougall said: "This film speaks of the increasing confidence supporters of staying in the UK are feeling with one month to go.

"This broadcast shows we have a positive vision. We can have the best of both worlds. That means more powers for Scotland without taking on all the risks."

Yes Scotland chief executive Blair Jenkins said the polls were narrowing in Yes's favour.

"Opinion remains fluid, with everything to play for on September 18. Just over a month away from this decision, the people of Scotland are still none the wiser about what new powers, if any, Scotland is guaranteed in the event of a No vote."

A study presented at Holyrood's Festival of Politics yesterday found 70% of voters did not believe either the Yes or No camp could predict the consequences of independence.