When Victor Hugo died, his coffin was followed by a crowd that outnumbered the usual population of Paris. Tony Benn's funeral today will not be followed by any such numbers but it ought to be.

There are few figures who can fill an epoch with ideas, humour, hope and inspiration in the way Tony Benn has done.

Fascinating as they are, Tony would never have entertained a claim that his diaries transformed the shape of a nation's literature or gave him the status of a visionary poet. But like Victor Hugo, he became a symbol of both the nation's virtues and its vices.

What Tony would have hoped for, however, was a simpler acknowledgment that he tried to change the way we think about ourselves, the Earth we live on and our ability to transform its future.

On the last day of his life, Tony lay propped up in bed at home. Surrounded by his family, he was still sporting a snappy T-shirt proclaiming: "Saying no to the Poll Tax, 1381."

It was typical of the man - turning up on the right side of an event 500 years before he was born.

He was the only person I knew who could walk you through 2,000 years of history and leave you with the certain belief that he was present at every one of the moments he touched on. It was this ability to invoke the past, to inform the present and transform the future that made him such an outstanding and inspirational communicator.

My greatest sadness is that never has the world been more in need of the voice it has just lost.

There are still voices around who can hold a crowd, command an audience, lead a resistance. But Tony was the only one to make you feel that it was you and I who were the ones who might actually change the world.

This was why he was reviled by those most wedded to an elitist politics already heading towards a crisis of its own making. They were terrified of social movements that might invert the status quo and build something better by themselves.

Some of those who most disliked Tony Benn at least had the excuse of believing that at the time social democracy, rather than socialism, might deliver the answers any "decent" society was looking for.

The subsequent marketisation of everything that moved destroyed most of the credibility of this claim. Climate change will destroy the rest.

Once politics became obsessed with individualism and we lost the overriding collective sense of being stewards of a fragile planet, it was only a question of which crisis would be the one to break the camel's back.

Tony's fear was that without a clear alternative we would end up on the wrong side of history, failing to heed Rosa Luxemburg's prediction that the future would be a straightforward choice between socialism and barbarism.

He knew that with the right-wing press there could be no pardon or parole for the crime of wanting to distribute wealth more fairly, conduct government more accountably and pursue peace more intractably.

So he and his family endured the decades in which reporters rooted through their rubbish bins or perched in trees hoping to snap bleary-eyed photos of them. To avoid the issues, he knew that the press would always want to play the man rather than the ball.

Yet it was Benn's defiant voice and vision that brought large numbers of young and idealistic people into the Labour Party. His was the imagery that tied together the disparate strands of social activism that different social movements brought in with them.

Even MPs who moved rapidly to the right in the decades that followed acknowledge the uplifting sense of hope and connectedness that Tony scattered around, the cargoes of intellectual contraband that he carried from meeting to meeting.

Critics say he missed his greatest opportunity, failing to stay on board with new Labour once it had squatted inside the Labour Party following John Smith's death. But Tony knew that this was not just a shift in the balance between left and right.

New Labour was always more of a Tupperware party than a political party. It was a marketing product, anxious to move a fast as possible from socialism to social-ism.

Tony knew that those willing to remain loyal to "the project" would be asked to do so at the expense of some of their deepest beliefs. One by one, collective rights fought for over centuries would be replaced by individual rights, underpinned by means testing. Old solidarities would be replaced by aspirational insecurities. Tony's role was not to prop this up but to be the pivotal voice of a different sort of future.

It is easy to say that Tony Benn was the best leader the Labour Party never had. He would not have led the country into illegal wars, never have been a bag carrier for US neocons, never have turned his back on an economy that made things rather than money and never have stripped citizens of rights in order to protect the secret state.

The mistake in such an approach is that it would define the man through a set of negatives, when Tony himself was an abundance of positives.

Throughout the 40 years in which he was my minder, mentor, best mate and Best Man, Tony brought laughter and hope to everything he touched. He would light up a room just by walking into it. Within minutes he would have everyone feeling so much taller than we were. Part of this was his ability to have us laugh at the absurdities surrounding us.

I remember a highly charged meeting in the early 1970s, when Tony was challenged about his position on Rosla, the raising of the school leaving age to 16. His immediate response was to declare a preference for the leaving age to be 80, claiming that education should be a citizen's right "throughout our lives."

At another school meeting where parents had been discussing various ways of boosting school funds no-one was expecting that, when asked for his thoughts, Tony would quip: "Well, have you thought about prostitution? And I know I have a weakness for Mars bars from the tuck shop but I understand that crack cocaine has a much higher street value."

A moment of tangible silence followed until he continued: "You see, call me old-fashioned if you like, but I've always thought education should be funded from taxation rather than as a trading commodity." People laughed - in relief - then cheered, in appreciation of the debate being moved to where it should be.

Tony always refused to be trapped within parameters defined by the right. He knew how warmth and humour could empower his friends and discomfort his enemies. And, by insisting on a right to debate issues on different terms, he freed others to do so too.

In the week of Tony Benn's funeral, all of Labour's think-tanks, left and right, called on the party to stand for something bolder. It was a call Tony never turned his back on. Age radicalised and emboldened him. Humour, insight, kindness and clarity broadened his appeal. Labour has to do the same.

And, as someone forever fascinated by technologies, Tony also grasped that today's innovations might open up possibilities for us to live more lightly through the turbulent times ahead, if only we remember how to share.

This has to be Tony Benn's enduring legacy, not as a ubiquitous part of the past but as a toehold into a better future.

Tony will live on as a disruptive inspiration, not as a national treasure. To the last, he insisted that we are indeed each other's keepers - the custodians of our best hopes and brightest dreams. This will be so, whether Labour's leadership grasps it or not.

So, when the T-shirt fades, the pipe gets forgotten and the diaries are out of reach, how do you pay tribute to someone so much bigger than the time he lived in?

The greatest tribute to Tony Benn's life would be for us to be as brave and as bold as he believed we could be. This would transform a loss into a blessing.

It is never too late to pick up the mantle.

Alan Simpson was Labour MP for Nottingham South from 1992-2010 and now campaigns on environmental issues