A MARCH through Edinburgh to a rally in Princes Street Gardens today in support of independence will be scrutinised as evidence of the depth of support for a yes vote at the referendum in 2014.

The event has been organised independently of the official Yes Scotland campaign or the SNP and has a wide cast list of speakers, prompting claims behind the scenes that the SNP hierarchy and Yes Scotland campaign are playing it canny when it comes to backing the event.

But the fact that Alex Salmond will be there as keynote speaker rather gives the lie to that, as he said: "The march and rally in Edinburgh is another important step on the road to completing Scotland's home rule journey."

Also speaking will be Dennis Canavan, who chairs the Yes Scotland board. "This is the start of a long march towards our goal of Scottish independence," he said. "An independent Scotland will mean a better future for the people of Scotland because independence will enable the people of Scotland to shape that future.

"By participating in this event, you will be demonstrating your commitment to the cause. You will also be helping to make history."

Organiser Jeff Duncan, who cut his teeth on the campaign to save the Scottish regiments, made clear that he was refusing to predict turnout or "play the numbers game" as any figure he gave would be a hostage to fortune.

"We honestly don't know," he said. "It's not an annual occasion or a ticketed event so we just cannot predict the numbers. We know from the number of buses hired that attendance will be in the thousands, but we don't know how many thousands."

He is already talking about similar events next year and in the month before the referendum itself in 2014, when he plans to mobilise a huge gathering. "Those who join this year's march and rally are in effect the advance party, heralding the start of that national effort to mobilise supporters for a historic event in 2014," he said.

The event will meet in the Meadows, south of Edinburgh city centre this morning, marching at noon through the Old Town and down the Mound onto Princes Street before the main event at the Ross Bandstand.

There are 20 named speakers for the event, which may test the resilience of some waiting for the 10 bands who will be performing. Among those speaking will be Allan Grogan, founder of Labour for Independence, which now claims almost 1000 backers.

Green co-leader Patrick Harvie said: "I look forward to voting yes in 2014 not out of nationalism, but out of the conviction that the transformation which I believe Green politics represents, can best be achieved by Scotland as a small independent country."