On another crisis-strewn day for the government, Charlie Whelan logs on to his computer, not for a grim update but to check the weather conditions in the Highlands. "They're expecting gales," he says. Outside his Covent Garden office, something of that wind from the north is whipping the faces of London's home-bound commuters.

Whelan sits back in his chair and swings his feet on to his desk, coughing chestily and complaining that ever since he took up his new job he's had one cold after another. "When I worked for Gordon, sometimes 24 hours a day, I was never ill. But I must have lost my immunity in Scotland."

Until last September, the pugnacious former press secretary to Gordon Brown at the Treasury was rusticating contentedly on Speyside, pursuing his love of fishing and tweedily adjusting to the gentler rhythms of Dulnain Bridge, his adopted village between Grantown and Carrbridge. And just when this unexpected character change seemed permanent, Britain's biggest trade union came calling, offering Whelan the new post of political director of Unite, the name born of the merger of the Transport and General Workers Union and Amicus.

So, almost a decade after leaving behind the black arts of spin, and his notable rivalry with Alastair Campbell, Whelan is exercising his political clout again. Not that he has forsaken Dulnain Bridge and "the best salmon river in Scotland". He returns there at weekends, having worked out of Unite's HQ from Monday to Friday. Yet why leave the place he calls paradise to step back on planet soundbite?

"Gordon became Prime Minister, didn't he?" he says. "I admire the guy and I'm up for doing anything that can help in a small way." Does that mean he's become a sort of spin doctor emeritus, nipping in the back door of Number 10 to impart needed tips on image and presentation? Whelan scorns the suggestion. "Total rubbish. Obviously, as political director of Britain's biggest union - two million members, 120,000 of them in 14 marginal seats - I'm liaising with the government and working in those marginal constituencies towards the next General Election campaign. It's part of my job to have chats with Gordon but I'm not going to hassle him, am I?"

Certainly there is no shortage of that already, with ministers allegedly conspiring about who should replace a "jinxed" Prime Minister, and sections of the media hellbent on hostile coverage. "All absolute tosh," responds Brown's fierce loyalist. "I'm afraid there's a free-bar media that have got nothing better to do. I've met most of the Cabinet in the past few weeks and it's remarkable how united they are. As for replacing Gordon, only a bloody lunatic would do that."

Yet given the government's demand for public pay restraint, Whelan will surely have to hassle the prime minister on behalf of his members?

"Well, I doubt if Gordon will lose sleep over the fact that I might disagree with him." But what about the present dust-up with 220,000 local government workers in Scotland threatening to strike after their unions, including Unite, rejected a three-year pay deal the other week? Cosla, which represents local authority employers, maintains that the unions have reneged on an agreement reached in principle, but Whelan's only comment is robustly succinct: "Well, they bloody would say that, wouldn't they?"

His retreat to Scotland six years ago came after that fractious Westminster period when Whelan was enmeshed in accusations that he'd leaked details of Peter Mandelson's £373,000 home loan from the former Paymaster General, Geoffrey Robinson.

No stranger to controversy, he has always denied responsibility for the incident, but even before the revelation -which led to Mandelson's second swift exit from a Cabinet post - Whelan knew his position was becoming untenable.

For months, Blairite ministers had put it about that he was undermining Tony Blair by stirring the old enmities between the Prime Minister and the Chancellor. As a result, Whelan was perceived as a press secretary who made the news rather than one who managed it. Amid ongoing acrimony, he quit and eventually headed north, leaving the media storms to others.

In Scotland, he recently combined his passions for angling and the country in a Radio Scotland series, Charlie Whelan's Gone Fishing, in which he lured celebrities, including Robson Green, Chris Tarrant and Lord Steel, to join him on different rivers. "I'd really like to get Prince Charles along, but for him fishing is his very rare free time away from journalists, so it's difficult. But actually I know his spin doctor quite well, so maybe I can persuade him to put a word in."

It was the late Jimmy Airlie, of Clyde Shipbuilders, who introduced Whelan to the Highlands. "Every New Year we used to go there with Jimmy, and we always loved it. Some time after I'd left Westminster, Philippa, my partner, and I felt we'd really like to settle there. So we decided to sell up in Peckham and buy a house on Speyside. And it's been marvellous. Philippa works for Unison in Inverness and I fish and play golf."

There is, of course, more to Whelan's relocation than that. Last year he was among 200 residents marching to demand that the Cairngorm National Park Authority and other bodies, including VisitScotland, reinstate Dulnain Bridge on tourist and community maps. The omission, more oversight than snub and now corrected, was terrible for local business, he says. "The trouble was that once we were left off the maps, it kept on happening as if the village was invisible, a myth."

And, as he is a man who can't resist a fight, enter Whelan the scourge of Scottish Water, whose proposed £15m water treatment scheme at Aviemore would change the source of the area's water supply. Whelan and the fishing fraternity insist the plan be scrapped because they claim it would be disastrous for the Spey.

"The pipe that runs from Loch Einich into Aviemore provides all the water for Badenoch and Strathspey, but Scottish Water say there's not enough water in the loch, probably the deepest in the whole of Scotland." The real problem, he says, is that this pipe is leaking and it will cost a fortune to repair it. "So, the plan is to put a borehole down and take water out of the river system, the most detrimental thing you can do. Scottish Water have put out all this spin that there would be hardly any effect on the water table but it's nonsense to think that anglers are going to swallow that. I, for one, have been around too long to fall for such rubbish."

Whelan's use of the word "spin" is interesting. Clearly it doesn't take long for one master of news management to recognise it in others. Since we're on the subject, does he recognise now that the Blair era's commitment to spin was instrumental in the public's disaffection with politics?

"That's an example of media people's obsession with themselves. In the real world, the public aren't disaffected with politics. But every day, when I was working for Gordon, I would get about 200 calls from all these hacks wanting you to spin something so that they could spout more rubbish. You can't blame spin doctors because you journalists are part of it, and spinning is part of the political machine."

So, what accounts for the low turnout at elections? "We've got a media circus which doesn't cover politics in any meaningful way.

But spin doctors are nothing new. The difference is that under New Labour we were better at it."

Would the government's woes be any less if Whelan's muscular brand of PR were to hold sway? "What I did as spin doctor for Gordon was a manic 24-hour day, and it would be mad to go back to that. What I'm doing now at Unite is more measured. And I'm older and wiser. I mean, I don't think I'm naturally aggressive but these days I probably do regret having been so rude to people in the past.

"OK, the government is having a tough time, but politics is never easy. It's how you get through the tough times, and I think Gordon is coming through them pretty well." The difference between Blair and Brown, he says, is that Blair is a brilliant actor. "And Gordon can't act to save his life. But he's a man of substance, whereas David Cameron's PR spin has no substance at all. I used to like Tony. We'd have a laugh together, but I suspect Tony isn't loyal to anyone. He and Alastair Campbell lied about the (Iraq) war. That wasn't spin. That was just lying, and people knew it. Even in sleepy Grantown-on-Spey we had a big demonstration."

Has fishing made him a wiser man? "It's made me calm down a bit, taught me to be patient. Everyone should try it. I think Gordon should take up fishing." It is, he says, the biggest participation sport in Britain. "In fact, angling brings more money into Scotland than golf. And it's tremendously challenging and exciting, but until you have hooked into a wild Atlantic salmon on the Spey, I can't really explain that to you."

So, no surprise that when he goes down to the river with his pals, Charlie Whelan's BlackBerry is switched off, and all mention of politics is banned.