It is the perfect day to see Bath. Sunlight is bouncing off the honey-coloured terraces, tourists are picnicking down by the river, town-centre tennis courts echo to a thwack that somehow sounds more genteel here. But locals will tell you that, even on a day like this, there is a big black cloud hanging over a spot on the banks of the Avon right in the middle of the city. Underneath it sits the Rec, home of Bath Rugby Club, a place where gloom has taken up residence.

After a period of domestic domination that made Manchester United look like an outfit keen to share their toys, Bath last season found themselves within a game of relegation from the Zurich Premiership. In the end, thanks to a sly rule change by the league, no club went down. But that did not lessen the sense of shame; while Leicester, Northampton and even local rivals Bristol were developing and expanding in the new era of money, Bath, in the amateur days the epitome of professionalism, were floundering. The aristocrats of English rugby were on their uppers.

The club's response to vertiginous decline was to go back to the future. Jack Rowell, the man who led them to eight cup wins and five league championships in his 17 years at the Rec, has come back to be director of rugby. Eight years he has been away and he is now 65, a period of life when most people choose to equip themselves with carpet slippers and a good armchair. To some commentators his age and his past suggested only one thing: this was a nostalgia appointment, a cosmetic exercise, a desperate pretence that former glories had returned. Just one thing: if that is your analysis, don't tell Jack Rowell to his face.

"A relic, eh?" he says, looking down over his spectacles from a height approaching 6ft 5in. "That's what they say? Well, no. No. No. I'm here because people think I have the capability of stopping the rot and taking things forward. Let's say they believe I'm a trusted source of ideas who can contribute to the revival. This is not nostalgia. I wouldn't have come back for that."

So why did he return? Was he not aware that sportsmen, too, should adhere to that central tenet of the underworld and never return to the scene of the crime?

"Well, I thought about that a lot," he says, his north-eastern vowels barely softened by his years in the south-west. "Particularly because this ain't a magic wand situation. But a worthwhile challenge always interests me in life and Bath was bound to have some umbilical cord somewhere with Rowell. Given the state it was in last year, and where I was in my life, I could afford to do it, so it was a bit of a challenge. And there's the emotion. You don't invest 17 years of your life in something and then sit back and watch it go over the edge of the cliff. Plus I'm loving every moment of being back, so something must be right."

As statements of the obvious go, to say rugby union has changed in the eight years since Rowell's slow, steady step was last seen round the Rec, is up there with suggesting Nicolas Anelka doesn't smile much for a bloke with a bank account like his. Even so Rowell must have been struck by how much things have altered in the place he calls home.

"Funnily enough the process of running a club on the playing side isn't any different," he says. "It is still: What are your goals? How are you going to get there? Have you got the capability to achieve the goals?"

Where things have changed, he says, is off the pitch.

"I once got into trouble back in the early 80s saying we were in the rugby business," he recalls. "They had to get the smelling salts out in the committee room at that one. One committee member once said to me: 'Your trouble, Rowell, is you want to win every week'."

And he smiles at that: when the new season starts on Sunday, victory every other week would be a big improvement on last year. But if rugby is now a business, nobody is better equipped to handle its vicissitudes than Rowell. While he was the coach of Bath and England in the amateur days, he earned his corn as the chief executive of companies as big as Golden Wonder and Dalgety.

"Looking back it amazes me: when I was doing those jobs, flying all over the world, I reckon in 17 years at Bath I only missed 17 training nights," he says. "You say how could I do that when I was engaged in a very serious business career. Well, I'm afraid you'll have to ask my wife. Mrs Rowell will tell you. 'How come you are never available at home but you always have time for rugby?' - that was her question."

Rowell's speciality, appropriately enough given his present employ, was being parachuted into failing businesses and trying to turn them round.

"My chairman when I got my first chief executive's job said to me: 'Look around you at this company, Jack, the wheels are coming off everywhere. And that's the best time to take over.' I didn't believe him at the time, but he was right."

The most satisfaction he had in business, he says, was at Golden Wonder, reattaching the wheels to brands like Pot Noodle.

"That was so much fun, picking up something that had been in decline for so long. To lift the cynicism I found there and the run-down people assets as well as the run-down physical assets, that was a great pleasure," he says, with more than a passing nod to what he found at the Rec. "I remember once the factory burned down overnight. I'd been going round since I'd arrived saying: 'Everywhere you look there's an opportunity.' And as I stood there surveying the wreckage someone said to me: 'I suppose this is an opportunity.' You know what? It was."

Some might suggest it would require more than a firebomb under the clubhouse to revive Bath's fortunes. Indeed, as a troubleshooter, what does he make of the current health of the rugby business as a whole?

"Oh, under business rules you would have closed rugby down the moment professionalism came in," he says. "The players - not their fault - are being grossly overpaid compared to the cash inflow. Premiership gates increased 25% last year, sponsorship's on the up, but it still depends entirely on owners prepared to indulge their hobbies, to run it from the heart and not the head. Andrew Brownsword [the owner of Bath] and his equivalent: the game of rugby owes them a great debt. Frankly, without them, there wouldn't be a professional game."

Rowell, perhaps wisely, won't be getting involved in that side of things. His role is solely working with the players. While much of the day-to-day coaching will be left to his young Australian lieutenants Michael Foley, Brian Smith and Richard Graham, Rowell says he likes to go to the training ground every day and "add value". Always a brilliant one-to-one motivator (the best in the history of the game, according to Dewi Morris) his first task, he says, is to lift some of the chins of the better players.

"The peaks we face are Himalayan. My role as optimist-in-chief is to present them as merely Alpine," he says. "The first thing you do is stop the haemorrhaging. Bath have been going through destabilising influences, players wanting to go, clubs looking at the staff and thinking who they can cherry-pick. I have to give the players a future to invest in."

And can they see the future in the old warhorse in their midst?

"Well, they've been very friendly. Some of them are aware of the history of Rowell, but it's the future that counts. And I have made it clear that we only have half a squad and that, though everyone will be given a chance, we will have to bring new blood into this club. The squad needs an overhaul here."

There is a sudden glint of steel beneath the avuncular charm as he says that.

"Take the injuries we've been having. I've got five of my best players unavailable for the first game of the season. This plethora of injuries is not right, it shouldn't be like that."

But surely it is a much more physical game than eight years ago.

"Of course, like being mugged 30 times in 80 minutes, as they say in rugby league," he says. "So you have to prepare for that, in terms of diet, conditioning, in terms of hardening the upper body. Like so much here that was neglected. We have to look to how other sports do these things, how they prepare their athletes. I remember when I was with England I suggested to one of the coaching chiefs that we steal an idea from American football and have people up in the stands watching specific aspects of how our opponents were defending, information that was relayed back to the coaching team on the touchline. He looked at me and said: 'That's crap, Jack.' And I quote there. Well, those days are over."

He talks like the new kid on the block, awash with enthusiasm, anxious to indulge new ideas, implement new methodologies. Yet it cannot be avoided that he is 65. If, as he admits, it is a long-term job re-establishing Bath as a force once more, how long can he be around to see it through?

"Whatever it takes, one never thinks," he says. "If you're driven by a passion for the game, as long as you have the mental and physical stamina, it ain't a problem. Life's changing in terms of expectation of what you're supposed to do at what age. It's like the rock 'n' rollers; Mick Jagger's going on forever. I'm doing my best to do that."

At which he has to leave, hungry for more work. As he stretches up out of his chair, arms pushed close to the ceiling, it is noticeable he doesn't wear a watch.

"Never have," he says. "Mrs Rowell always said: 'How come you are an international businessman and you don't wear a watch?' But I look at the sun, I know where I should be."

And when you think about it, it is no surprise that Jack Rowell, the pensioner in a hurry, doesn't wear a watch. He wouldn't want anything around to call time on his fun.