On Wednesday, the oil company he founded almost 20 years ago, Tullow Oil, reported another year of bumper results. Heavey says he forgets how many years in a row that has happened.

It's probably at least five. This time sales are up by 98% on 2004 to £445m ( 646m), while 2005 operating profit is up by 250% to almost £199m ( 289m).

It is little wonder Heavey is in a good mood, even as he comes towards the end of a day of conference calls and meetings.

Likeable and chatty, the 53-year-old has made the oil business his life. Even the 5.30am starts haven't begun irritating him yet. His young family, one child aged six and two four-year-olds, keep him young, he says. Or tired, at least. But two decades since Tullow Oil started out as just another minnow, Heavey shows no signs of slowing down.

"I can't afford to, " he jokes. "I still have to put the kids through school."

It should be no problem. A hard slog, shrewd acquisitions and soaring oil and gas prices have seen the market value of Tullow balloon to over £2.1bn ( 3bn).

Heavey's latest reported holding in the firm is worth almost £21m ( 30m).

For a man who once described himself as a "crap" accountant (he was working as one prior to starting up Tullow), the irony of Tullow's success is not lost on him. Reminded of the self-deprecation, Heavey laughs. "Well, we've got a lot of very good accountants working in Tullow, so we're very fortunate that way".

His golf was pretty shoddy too, but Tullow's first major transformative deal . . . a £200m acquisition of North Sea oil wells in 2000 . . . was initially discussed while Heavey was playing a round with a banker who offered finance. "My golf is getting better, but my accountancy has never been that good."

It matters little at this stage. With an eye for deals, Heavey and his management team have expanded the company's footprint throughout Africa, across the North Sea and into India, Pakistan and the Far East. Among the major corporate landmarks was the 2004 acquisition of Energy Africa for over $500m.

Heavey stresses that to achieve what Tullow has done demands an open management culture. "It's not like The Apprentice, " he says, referring to the BBC show featuring a confrontational Alan Sugar, the boss of Amstrad, where one wannabe executive is unceremoniously ditched every week. "There's no blame culture in Tullow."

He attributes Tullow's success to getting the right balance. he says. "The board members are all good friends and the company is seen within the business as a good place to work. When we offer people jobs, they accept them." It might sound like a line from a Mario Puzo novel, but it's clearly not intended to.

The growth of Tullow has led Heavey to parts of the world even the most determined 20-something backpacker will never see. He says he has been to every country in Africa. Tullow's outposts . . . some offshore, others inland . . .

can be intimidating even in a world of aircraft and four-wheel drives. Last week, Tullow's outgoing exploration director, South African Adrian Nel, described a very promising but remote licence area in Uganda as "real David Livingstone country".

You're unlikely these days to find Heavey tracing the Nile. He still travels a lot, but he says it's mostly in a "diplomatic" capacity, meeting senior government officials and other vested interests. At 53, it's probably best that some of the more adventurous times, dietary and otherwise, are behind him.

"I remember once we had to go to an offshore oil rig in Ghana to have a look at it, " recalls Heavey of one trip. "We were supposed to get a supply boat to take us out and we waited on a beach, but it never showed up. We found out that it had holes and couldn't float. So, we went to the local fishing village and rented a dugout canoe. There were three of us and two guys with paddles bringing us to this oil rig four kilometres offshore."

Heavey says he ended up swinging about on a net dropped by crane from the old oil rig, with no way of getting off except dropping into what he says was a shark-infested sea. "You always get them around rigs."

Eventually, after making it safely aboard "for a meal that consisted of a prehistoric chicken and a can of some kind of vegetables", it was back into the canoe, now with a small outboard motor attached. "The waves knocked the engine off the boat and we were being pushed out to sea, getting soaked in our suits."

Six or seven hours later, he says, they got to shore, took off their wet clothes and got back into the four wheel drive to drive back to Accra. "We stopped at a roadblock just outside the capital and I can't imagine what the soldiers thought when they saw two guys in the front with two white Irish guys in the back in their underpants."

Such experiences do nothing to deflect from Heavey's love of his job.

"The oil business is fantastic. It's a great job to have. If I applied for it, I probably wouldn't get it."

As for the industry's future, Heavey believes high oil and gas prices are here to stay. And asked if he turns down the thermostat to save fuel when he arrives at home, he replies with characteristic humour. "I've got a natural hedge against increased oil and gas prices. It's called shares in an oil company."

He would recommend to anybody who's worried about energy prices to buy oil stocks. "Then, when you're filling your petrol tank and it costs twice what it did the week before, it will make you feel happy because your oil stocks have gone up."

Despite the mirth, the serious business of running a FTSE-250 company is always on the agenda. Tullow Oil will spend almost £280m this year on capital expenditure that includes redeveloping existing fields and developing new ones, while millions more will be spent on exploration.

Tullow expects its production to rise to roughly 75,000 barrels of oil equivalent per day by the end of the year.

There's undoubtedly enough to keep Heavey busy until retirement age eventually comes. He jokes that Tullow's rise has surprised him, but not as you'd expect. "Strangely enough, I thought we'd be there a lot sooner. I'm disappointed it took so long."