In caricature, he is a union baron. But no one ever elected a baron, and although the headquarters of Unite, Britain's largest private-sector union, with two million members, is located on King Street in Covent Garden, London, neither the offices nor the man are remotely regal or baronial. Derek Simpson is the elected joint general secretary of the all-powerful Unite, which has members, like fingers, in all the trades, from motor manufacturing to print and steel - even the British Airways cabin crew.
As New Labour's fair-weather friends have peeled away, Unite has found itself in a familiar position as financial nursemaid to the party.Consequently, Simpson - in concert with Tony Woodley, his fellow joint general secretary - wields more influence in the corridors of power than some in the cabinet might like.
Simpson was, as it says on the cutlery, "made in Sheffield", in the crucible of what was once known as the "Socialist Republic of South Yorkshire". Born in 1944, he left school at the age of 15 and served as an apprentice at a local firm, Firth Brown Tools. He moved to the engineering company Balfour Darwin in 1966, where he became a shop steward a year later.
His politics are uncompromisingly rooted in the factories, foundries and engineering works of the steel city. "You know, with the advent of New Labour, there was this pretence that something had to change dramatically in the party to get rid of the Tories. But this was a time when anyone could have beaten them," he says. "It was then taken by the New Labour people that it was all down to them, and the election victories that followed confirmed that it was down to New Labour successes. Nobody ever looked behind all of this to see that, in that time, we lost four to five million voters. And that's the slippery slope we've been on since."
Some of Simpson's younger aides might wince at this, but union members provided much of the ballast for each of Labour's three consecutive election victories, driving candidates to events, knocking on doors and sticking down envelopes. These people are hurt by the fracturing of a relationship between the party and the unions - once partners joined at the hip. "It's clear," Simpson says, "that the one thing the Tories did have was hatred of the unions, and the one thing New Labour didn't have was a love for the trade unions."
And what of his relationship with the Prime Minister, Gordon Brown? Is the reception in Downing Street any warmer than it was under Blair? "Gordon is much more approachable than Tony Blair was. We had access to him, of course. When it comes to 'Hail fellow, well met', Tony Blair takes some beating. But Gordon is still locked into much of New Labour. After all, he was an architect of it."
I'm sitting next to Simpson in his modern office; a stained-glass window is emblazoned with the logo of the old Amalgamated Engineering Union. He had the window rescued from the union's former offices in Peckham, south London.
Does this represent traditional values in a modern setting? He smiles. "Gordon is trying to do two things. He's trying to hold New Labour together in a situation that demands Old Labour, and that summarises Labour's plight. [It] explains why those ex-ministers tried to perform a coup - because Gordon has to move down an Old Labour path now. That's why the New Labour types are clinging on by their fingernails."
Simpson was something of a latecomer to the Labour Party. His mentors back in Sheffield, when he was active on the shop stewards' committee, were Ted Scott, Albert Knight and the best-known trade unionist and communist in the city, George Caborn, father of the former Labour minister Dick Caborn.
In the 1960s and 1970s, the industrial wing of the Communist Party of Great Britain (CPGB) was a powerful force in the northern industrial cities.Simpson was a member. When he was elected to the executive committee of the AEU, he was exposed to the stirring oratory and organisational abilities of better-known CPGB members such as Jimmy Reid, leader of the Govan shipyard sit-in, and the much-lamented Jimmy Airlie. (Unite's headquarters were once home to the CPGB.)
“I remember travelling to London to hear the likes of [the AUEW leader] Hugh Scanlon," Simpson says, "but I would dispute that I was ever well known. I never thought that I would ever be a leader of my union."
Simpson's victory over "Tony Blair's favourite trade unionist", Ken Jackson, in June 2002, was as much of a surprise to him as it was to everyone else in the labour movement. His emergence as the leader of what was then known as Amicus - the result of several mergers between unions such as the left-leaning and democratic AUEW engineers' union and the hard men of the right-wing electricians' EETPU - is one of the more remarkable tales of triumph over adversity.
It probably also explains why Simpson sits so comfortably in his own skin. "Anyone who stood out didn't attract much favour with the leadership," he says, with glorious understatement. "That included me!"
Various officials tried to persuade Simpson, who had to give up his union job to challenge Jackson, not to stand for the leadership. "They shut the Sheffield office. They moved me to Derby; they offered me other jobs; they wondered if I felt 'ignored' or 'left out'."
Simpson, the outsider who had kept himself to himself, in effect remained the last man standing as the union machine purged other leftists like him. "There weren't many prominent ones left, and I mean left," he recalls. Of the day of the actual ballot, he says: "It was close. On the recount, I discovered two ballot papers on top of one of the bundles of 500 in elastic bands that were marked for Jackson. The other 498 were for me. You have to ask how that was possible."
Despite - or because of - his travails, Simpson, to borrow a line from Michael Caine in Get Carter, retains his sense of humour. His relationship with his opposite number, Woodley, the product of yet another merger between the Transport and General Workers Union and his own Amicus, has at times been troubled. But as the interview draws to a close, the tough former union negotiator comes into the office. "Did you hear what I said when I followed Tony at the Labour party conference?" Simpson says. "It's Unite from him and it's Unite from me. Unite!"
Unite, which has a global presence after forming a relationship with the US steelworkers' union - something that Simpson is proud of - reputedly holds a political fund of as much as £8m. Members, unlike company shareholders, are required by law to vote on whether they want a political levy. The money is taken from union subscriptions for union campaigns and affiliations to the Labour Party.
“Now, I've seen some fantastic figures as to what we give Labour," Simpson says, "but we don't give affiliation fees on the basis of buying policies. Imagine what the Tory papers would say if we did."
Labour is now deep in debt and dependent on the unions for as much as 60 per cent of its funding, as rich donors abandon the party and membership continues to fall. If it loses the election, Unite could become its near-sole proprietor. "That's doomsday talk. I don't think it will happen."
But Simpson acknowledges the strain between the party and the unions that has led the National Union of Rail, Maritime and Transport Workers, as well as the Fire Brigades Union, to disaffiliate altogether. "As much as the party deserted the unions during the New Labour period, so the unions have deserted the party. But I say there are more of us than them; all we've got to do is turn up and get candidates selected that, if you like, are more traditional."
By that, Simpson means working-class, "local" people who are aware of what he calls "real life". He is irritated by the "professional New Labour" types. "You see, now, when you go to the selections, [that] the local-accented, not necessarily university-educated, and 'aware-of-real-life' people don't seem to stand a chance against the clean-cut, smooth-talking, 'well-supported-by-the-party' people, who are just being parachuted in."
What if David Cameron wins the election or forms a minority government? Would Unite talk to the Conservatives? Simpson blanches. “I come from the old school. I don't think there is any advantage in talking to the Tories at all. You are just going to get whatever they are going to give you. Quite frankly, it's just waffle. Fortunately, since I'm in my final year [he steps down as leader in December], I won't have to be in that situation. Which is why I told Richard Balfe [Cameron's trade union emissary, a former Labour MEP] to get lost."
But what if there were some moderate Tory MPs who might be prepared to be swayed by the union's arguments? "The idea that they have changed is completely wrong. Lord Ashcroft - he's basically bought the party and is waiting for power. The cabinet wouldn't be able to resist whatever Ashcroft wants. They are already mouthing off about what they are going to do about the unions. I just wouldn't talk to them, personally. Waste of time. There may be some who will talk to them, and if the Tories are clever, they will toss a few crumbs from the table [at the unions]."
Simpson has long been a supporter of Brown and was dismissive of the various challenges to his leadership, particularly the one from the Foreign Secretary, David Miliband. He is not, however, so dismissive of David's younger brother, Ed. "In my view - and this is a complete quote, not part of a quote - I'll be perfectly happy for Gordon Brown to continue as long as he wants and, by that time, I suspect that Ed Miliband will be experienced enough to warrant my support as Labour leader."
It has often been said that another aspirant Labour leader, Ed Balls, would have Unite's support. But clearly it is Ed Miliband, and not Balls, who is now the chosen one, Labour's leader-in-waiting, if Simpson and his friends have their way.
What will Simpson do next? "Derek's got no idea what Derek does next," he says, oddly switching to speak about himself in the third person. "Derek has never planned a future. I didn't plan to become a general secretary. There are lots of things in life I've ended up being too busy to do. Maybe I won't live all that long, either, since I haven't exactly lived a healthy lifestyle. I just expect it will be a bit of a culture shock for me - [switching from] what I do now to next to nothing.
“The epitaph I've got is what my old mentor Ted Scott told me: 'If you can leave it better than you found it, you've done a good job.' I reckon when I leave this union, it's better than when I found it."