Since their first meeting in Trimdon more than ten years ago, Political Editor Chris Lloyd has seen difficult times take a physical toll on our youngest modern-day Prime Minister, who reaches the grand old age of 50 today. But he still retains his ability to bounce back

TONY Blair is a man of many enigmas. Does he really support Newcastle United? Does he really hold his mug of tea by the top rather than the handle out of pure habit, or does he just think it looks cool? Can he really play the guitar? And what, if anything, does he believe in?

The answer to the first question is probably yes (when his agent John Burton was asked recently what the best present would be for Tony's 50th birthday he replied Alan Shearer's signed No 9 shirt); to the second, habit (judging by the number of pictures you see of him standing up and dipping his thumb in his mug); to the third, yes, he can play guitar - when we last met he told me he'd played an old rock 'n' roll number called Shake Me at a party thrown by George Bush at his Texas ranch ("it was just basic 12-bar," Mr Blair said dismissively). The fourth question is a little harsh. After all, he has just gone to war because he believed it was the right thing to do - even though the polls said the majority of the British people disagreed with him.

Another question people always used to ask about Tony Blair, was how could a man who was Prime Minister look so young?

I first met him more than ten years ago when there wasn't a wrinkle on his face and there wasn't a spin doctor in sight. He was a shadow back-bencher and had been working on the Plant Report which, back then, was long-awaited and extremely important but now seems instantly forgettable.

He clung to the radiator in his study in his house in Trimdon and rolled out, unstoppably, his hopes, dreams, ambitions and aspirations. The interview went on so long - his secretary kept popping into the room to tell how many trains from Darlington she had missed while he had talked - that towards the end I must admit (to my regret) that I was only half-listening.

My attention had been taken by his jumper - a light blue mass-produced V-neck which was both unfashionable and unflattering. It was made of a clingy material that showed off the beginnings of a little round belly. Only now that I approach the age he was then do I realise just how young that jumper made him look: he was so young that he was still in denial about what the onset of middle age does to your body.

But age caught up with him dreadfully four years later during the 1997 General Election.

Midway through the campaign, I met John Major, probably in Stockton, and was amazed by his composure and the utterly English perfection of his appearance.

He wore an immaculate blazer and a pressed cricket club tie. He was superbly shaved - not even a hint of a hair on his distinctive upper lip - and his silvery hair looked so soft and downy that I longed to stroke it.

Most impressive of all, though, his large glasses had been buffed to the point of brilliance so that they shone like no spectacles have ever shone before.

But then Mr Major had nothing to lose. He had won in 1992 against all expectations and this time everyone knew he had no chance at all. In fact, the way his Government had sleazily staggered towards its demise, he probably knew it would be a blessing if it were put out of its misery. And so he could afford to be relaxed as he maintained his personal dignity but looked ahead to a place out of the limelight.

By contrast, a couple of days later, Mr Blair was on the patch at Trimdon and the weight of expectation - of his party, of his country - was weighing as heavily on his shoulders as if he were giving John Prescott a piggy-back.

It was windy, and Mr Blair, poor fellow, does suffer from wiry flyaway hair. He got off his battlebus outside the Labour Club to be met by a big gust which tore at his face. He smiled his peculiarly goofy grin with his chin stuck out, and his red tie leapt out of control and over his shoulder. He kept tugging at it to keep it down, but in the gale it had a mind of its own.

While all these bits of his body were being blown up, up and away, the bags under his eyes were dragging down to the floor. He had shavers' stubble spread across his red cheeks and his jacket pockets were so baggy it looked as if he'd been keeping half-a-hundredweight of Mr Prescott's favourite boiled sweets in them.

Whereas in 1993, he had looked young enough to be a part of my generation, he'd suddenly aged and become a part of my parents' generation.

He was tired, I was told. He needed his sleep. He'd been on the road for weeks, and needed his bed.

And it worked. When I saw him less than a week later on May 1, 1997, as he strolled out to vote, walking casually across the meadow behind his house, I saw a lean, young man who knew exactly where he was and exactly where he was going. With his youthful family around him and the wiry bits cut out of his hair, he looked not to have a care in the world nor a line on his face (although that peculiar tooth has always been there, set back in his lower jaw).

Indeed, the only other time he has appeared as old as he did in 1997 was earlier this year when the bags were back under his eyes and his skin had taken on an unhealthy pallor.

He was tired, we were told, he'd been up for days on global diplomatic shuttles and trans-Atlantic calls, trying to avert a war while being one of only three world leaders in favour of conflict.

But once he had made his decision, once he had committed his troops and once he had made it into bed, all the stories about the terrible physical toll the war was taking on him disappeared as if they had just been a bad dream. The youthful effervescence returned - the leap, the bound and the big Blair beam.

In fact, here on his 50th birthday, all the newspapers are asking how the Peter Pan of Politics, the Cliff Richard of International Affairs, remains so eternally youthful.

If he could find a way to make his sleep available on the NHS, Alan Milburn would save drastically on his health budget.