One is the suave servant of Her Majesty’s government. The other is a brute assassin, the rogue employee of a now defunct agency of the FBI.

One prances around in a bespoke dinner suit, custom underwear by Sunspel and La Perla swimming togs. The other wears a holey sludge-coloured fisherman’s sweater and the kind of schlumpy outerwear seen on teenage French exchange students. One has an arsenal of turbocharged vehicles and technical gizmos at his disposal, the kind of gadgets that can fire laser beams or emit piercing loud noises when needs arise. The other is really good at reading maps.

Only one of these men is even remotely stylish. And it isn’t the one driving an Aston Martin. An anti-hero hero for a modern age, Jason Bourne leaves James Bond in the shade.

Matt Damon, the 45-year-old actor who plays him, summed up the difference between the two men in a recent interview. “Bond is a misogynist who likes swilling martinis and killing people and then telling jokes about it. Jason Bourne is a serial monogamist — he’s tortured by the things he’s done and feels empathy and compassion for other people. And Bourne would obviously win in a fight!” Obviously.

Jason Bourne, the new instalment of the Robert Ludlum-based thriller series, debuts onscreen on July 27. And I, for one, am counting the hours until his arrival. It’s been 12 long years since we last saw him, floating around in the Hudson River. During that time his cinematic rival 007 has been recast, rebooted and retired again, while Bourne has remained deep undercover. Arguably he was keeping scarce until all memories of the ghastly Bourne Legacy, a horrific attempt to sabotage his reputation and rebrand the franchise in 2012, were fully erased. Unlike Bond, who shapeshifts with ease, the actor who plays Bourne has proven stubbornly irreplaceable.

He returns a changed man, to a changed world. According to Damon, this Bourne outing will find him “rolling around in the detritus of modern-day capitalism”. He’s now older and freakishly muscular: on-set images and trailer footage have found him as ripped as a cage wrestler. His expression has hardened as well. Gone is the youthful naivety of yesteryear; today his features are carved with knowing. “I remember everything now,” he growls.

But he still makes me swoon. It’s incurable: I’m Damonted, Bourne again and Matt about the boy. Always have been. Always will be. For my money, Bourne is the greatest cinematic action hero since Steve McQueen in Papillon (1973), or Clint Eastwood in Dirty Harry (1971). He’s stylish without being showy. Brainy without being boorish. He’s not vain: in fact, he’s always seemed vaguely repelled by his own reflection. His style expresses nothing other than a desire to remain invisible — dark, anonymous tops, bomber jackets, military boots.

But what I adore about him is that this most alpha of males doesn’t act at all alpha. He doesn’t posture, or preen, or spend time fetishising firearms or sexually harassing women. He just does it. No fancy getaway car? He’ll make do with a stolen Ford Mondeo or an old banger. He might occasionally insist on driving: but only when your life is actually in danger.

Bourne doesn’t do tricksy. Or cute. And while he may lack Bond’s queasy bonhomie, he can still drop a great one-liner (“Get some rest Pam. You look tired”).

Better still, his heroics are bound up in hilariously prosaic acts of behaviour: an ordinary bloke, trapped in a bionic body. Who would have thought, for example, that checking out the emergency exits on entering a bank would be a great mark of manliness? Or that taking a moment to inspect the timetable on arrival at Kievsky train station would allow you to perfectly time your aerial leap from a moving train on to a passing ferry?

His is a uniquely nerdy machismo. While Bond prats about with poisoned cocktails and exotic paraphernalia, Bourne studies the small print, which makes him inestimably cool. (Truly cool people don’t identify themselves as such.)

For me, the most thrilling moments in a Bourne film are those when he might be, say, limping through a Russian shopping mall having been shot in the arm and noticing that, yes he did remember to grab a floor plan off the wall to better speed his navigation. His pedantry is his perfection. And oddly aspirational: Bourne persuades us that if only we paid a little more attention (and had the benefit of a military brainwashing, photographic memory, iron strength and fluency in several languages), we too could be invincible.

Of course the new film may change all that. Bourne may be reborn an action hero of the old-school, all pomp and pump-action shotguns. The temptation to soup up the explosions and dial down the more mundane details of his expertise may have been too great for director Paul Greengrass, who returns to direct and produce the film with Damon. Some have hinted that my idol has evolved into a more predictable action hero. With all the designer trappings.

I really hope not. I adore Bourne for his geeky pragmatism. Newly pumped up, and mentally cognisant, it’s possible he may have finally learnt, like his narcissistic counterpart, to love himself. And that would be a tragedy.