SIZE, says Frank Chapman, looking as lean and sleek as a greyhound, is not important. Well, you could have fooled me. For a boss whose business is sprinting ahead right now, you would think size is one of the mission aims carved above the firm’s front door.

For one thing, doesn’t size make you less likely to be taken over by someone bigger? “Well, maybe,” grins Chapman, “but it’s not something I spend a lot of time thinking about.”

Really? Chapman, the former Shell high-flyer who has been chief executive of BG for four years, just raises his eyebrows and shrugs. And who can blame him for being confident? He has just released first-quarter results that are ahead of forecasts. These follow a leap in earnings and turnover (£3.6 billion) at BG for 2003.

On a broader front its business — finding and selling natural gas round the world — now looks on the button as countries search for more eco-friendly alternatives to oil. And compared with the bigger and more established FTSE 100 giants BP and Shell, BG — spun out of the old British Gas — is surging ahead in earnings growth and reputation. Many now rate Chapman as one of the top bosses in Britain.

And there’s the rub. Chapman, an engineer turned manager who has spent more working years abroad than at home, is in that awkward position of doing so well that all sorts of people want a chunk of him.

Earlier this year the City was awash with rumours that he was exactly the man Shell needed to sort out its problems. Those followed half a decade of whispers that many of the oil giants, including Shell, had run a ruler over BG as they thought about increasing their exposure to gas. Maybe Shell would have to buy BG just to get Chapman? Now that would be flattering.

So far, it hasn’t happened, and it would be a change of style for Shell if it did. For a start Chapman, 51, son of an East End lorry driver, seems rather less patrician and more approachable than most bosses at the oil giants. Tall and thin, snappily dressed in a blue check suit, his pinched features set off by an earnest charm, he is as happy chatting about how travel opened up his own horizons as he is about midstream, downstream, and other oily technicalities such as shipping LNG (liquified natural gas — one of BG’s big growth products) halfway round the globe.

In fact, the only thing he does not want to chat about, sitting in an armchair in his spacious second-floor office at BG’s Reading business-park base, is Shell.

“I haven't worked there for nine years,” he sighs, “so if you want a comment, I think you should ask them.”

Oh come on, I have to ask if he could be tempted back? “And I have to say I am not going to comment,” he laughs.

Those close to Chapman confirm he is too involved in creating his own business to want to leap into somebody else’s right now. BG was set up with a blank sheet of paper for future strategy, one of three plcs born out of the slow dismantling of British Gas (the UK retail side became Centrica, and the UK pipeline business was renamed Transco). Chapman, working closely with former chairman Sir Dick Giordano, had the chance not just to reshape the the business, but also to revive morale at the organisation.

And that makes many think he will stay there, especially as, so far, his decisions seem to have paid off. BG has concentrated on getting gas out of the ground and shipping it to key markets in Europe, North America, Brazil and India.

Along the way, it has not been frightened to sell off important oil finds, if offered enough cash, or to invest heavily in new initiatives, such as the growing market for LNG (liquifying gas, transporting it by tanker, and re-gassifying it where demand is high). All the time, says Chapman, the emphasis has been on selling, not finding.