As tragic heroes go, former Prime Minister Gordon Brown's downfall was one of the most public examples of vaulting ambition gone wrong.

This is gold dust for drama, which award-winning journalist and filmmaker Kevin Toolis has taken full advantage of in his forthcoming Edinburgh Festival Fringe play, The Confessions Of Gordon Brown. While this solo work, performed by Ian Grieve, is ostensibly about Brown, as Toolis explains there's a lot going on beyond the purely biographical.

"The first job I ever had in 1983 was as a parliamentary press gallery reporter," he says, "then I did a lot of work in Northern Ireland and in the Middle East. I encountered a lot of political structures and a lot of political leaders, in all different shapes and formss.

"I was always very interested in leadership, and in Gordon Brown. I think the play began when I was listening to BBC radio one night, and someone said that when he was in power, Gordon Brown was a Shakespearian tragic figure, but no-one could actually tell you from which play. He was a combination of Richard II, Hamlet, King Lear and Macbeth.

"Some of the things he did were a bit indecisive, but he was also a very good man. He's a much more complex human being than Alex Salmond. I could never do The Confessions Of Alex Salmond, or even Tony Blair."

Toolis reckons that the people that we have chosen as our leaders from the beginning of time tell us much about the universal traits of society. "In a way, you would recognise the same things in every political manifesto," he insists. "The future's going to be better, our city shall shine upon the hill, we shall be victorious and, tomorrow, crucially, the sun will rise from the east.

"So the play's about Gordon Brown, but it also has a universal quality, I hope, which looks at who are these people we've elected leaders, and why we have such faith in them."

Toolis has made something of a life study of political structures. His book Rebel Hearts: Journeys Within The IRA's Soul is regarded as a definitive study of the Irish Republican movement, and he has also reported widely on conflicts in the Middle East.

As with all his work, The Confessions Of Gordon Brown is as much about belief systems as anything. Following I, Tommy – Ian Pattison's comic study of disgraced former Socialist MSP Tommy Sheridan – Toolis's play is the latest stage work to look at living politicians.

"It's not an authorised biography," Toolis says, "and it's certainly not a hagiography. What I did do was to speak to large numbers of the Labour Party, significant members of Mr Brown's leadership circle, from Douglas Alexander to Ed Balls to Damien McBride, and to many other people who would be on the fringes of that circle. It's not a documentary. It's an artistic interpretation, both of the man and of the universal king, and aspects of leadership."

Given Mr Brown is still very much alive and kicking, if keeping a low profile these days, what would he make of Toolis's play?

"I've no idea," says Toolis. "Gordon Brown has something of a reputation for being a thrawn king, but the play is empathetic. It's a dramatic interpretation of an important issue which transcends Gordon Brown, and is about what it means to be a leader.

"There's a relevance there too to what's going on in Scotland right now with the forthcoming referendum. If Scotland goes independent, that will basically be about belief in Alex Salmond as the undisputed leader, who will lead us into the promised land.

"The choice of leader, and the faith that the led put in the leader, is absolutely crucial. The play examines that in great detail. We put these leaders on a pedestal, and that's partly a problem with us, because we want to be led."

The Confessions Of Gordon Brown, Pleasance, Edinburgh, July 31-August 26