The boss of Ryanair has flown me all the way to see him and I’ve lost my pen. “Not a problem,” says Michael O’Leary, in his light Irish brogue. “I collect biros from hotels, take your pick.”

He throws me a clutch of 10 or more. Hilton, Radisson . . . “I banned us from buying biros a few years back,” he grins. Now his staff are encouraged to find their own instead. And that, of course, is typical O’Leary. Boss of Ryanair for 14 years, still only 47, he has built his budget airline into one of the biggest in Europe by doing everything differently: cutting costs, slashing prices and abusing rivals in the process.

And soon, he says, Ryanair will be the biggest airline in the world, and if you don’t like it, tough. It is already the biggest international carrier in terms of “bums on seats”, with 49m passengers carried last year, and will eventually outstrip rivals who currently carry 100m, including domestic journeys. Just give him a couple of years and a good recession . . .

Anyway, first the pleasantries. Trim and affable, O’Leary is waiting in reception at Ryanair’s Dublin airport HQ to say hello, looking like the scruffiest man in the building — cheap jeans, check shirt, black loafers. His greying hair is restyled in a short mullet crop.

“How was your flight?” he asks. Bumpy and late. He knows already, reading from a scrap of paper in his hand. “It says the inbound flight at Gatwick lost 25 minutes unloading a wheelchair.” He pulls a face.

Then down to business. He wants to talk about his new bid to buy Irish rival Aer Lingus, based within rock-throwing distance of his office across the airport car parks. Ryanair bid £1 billion to buy it two years ago and was rebuffed. Last week O’Leary was back with a £635m offer, and is confident that this time he’ll get it. He gives me the sales pitch in bullet points.

“What is going on now is most of the second-tier European flag carriers are all looking to merge or consolidate with one of the big three: BA, Air France and Lufthansa. Aer Lingus is bypassed in that process as not of strategic importance to any of the big three, just an orphan. We believe that the only future it has is as part of one strong airline group with Ryanair.”

But Aer Lingus, Ireland’s flag carrier, is protected by a 25% government stake, and European regulators hate waving through monopolistic consolidation. O’Leary — who likes to call regulators “numbnuts” — shakes his head.

“With unprecedented crisis in the world, bigger national champions are the way forward, particularly if you’ve got a small, second-tier airline that has confirmed it’s going to lose money in 2008 and 2009.”

As for regulators: “This is the only airline merger in history that guarantees fare cuts and fuel-surcharge elimination. We are now the largest low-fares airline in Europe, dominant in most of the airports we serve, and we’re still lowering air fares because we’re growing rapidly.”

And that, he promises, will continue, however long the recession. Ryanair, hammered by high fuel prices, may make little money this year on revenues topping ¤3 billion (£2.5 billion), but it will bounce back into big profit next year, and keep expanding.

Isn’t that high risk, now the quality routes are mostly filled? He bats that aside. “I’ve worked through four recessions already and what happens is that we grow faster because everyone becomes more price sensitive. Passengers trade downwards from high-fare, fuel-surcharging airlines like BA to low-fare, on-time airlines like Ryanair.”