Criticisms of the young are usually dismissed as envious or grumpy, but no previous generation has had it so good, so there's plenty to envy, or grump about. We must also avoid encouraging the jejune notion that each generation is an improvement on its predecessor, so let's take a factual, grown-up, ungrumpy look at the new crop of politicians Gordon Brown's problems are thrusting into the limelight.

A glance at the fresh-faced David Miliband, David Cameron, James Purnell and Nick Clegg might make you think that the policemen are getting younger, and they are - not in age but certainly in appearance, demeanour and experience.

Our fortyish pretenders to power look nearer to 30 because they belong to a fortunate generation. No wars, better food and medicine, more exercise, financially unstressed lives, a bit of country living - these are the folk who will live to be 100.

They have other advantages. Meritocracy having stalled, aspirants to high office come from an increasingly small circle. Like Tony Blair before them, Cameron, Clegg, Purnell and Miliband are privileged folk, the ease of their ascent against declining competition there to be divined on their smiling, self-confident faces. Three were privately schooled. Miliband went to an “Etonian” comprehensive and, despite poor A levels, to Oxford. Daddy's name was no hindrance, one must assume, daddy being the Marxist theoretician Ralph Miliband, much venerated at the time.

Avoiding war, going to good schools and belonging to a longer-living generation is hardly our would-be prime ministers' fault. You could argue that we all stand to gain. Yet age-wise, things ought to be moving in the reverse direction. Logically prime ministers should be getting older, not just because their active lives will be longer, but to accumulate a little more experience before trying their hand at running the country. A doctor, soldier or businessman or woman might turn to politics at 45-50, becoming prime minister at a hale and healthy 60.

The young may object that this is older than the sainted Obama and John F. Kennedy, and that experience can be oversold. But the young forget that it was the 44-year-old Kennedy who authorised the CIA's Bay of Pigs invasion, helping to set the scene for the Cuban missile crisis, the most perilous in modern times.

With a narrowing of social background goes a narrowing of our young hopefuls' experience. Miliband was a wonk, Purnell worked at the BBC and wonked, as did Cameron, while selling downmarket shows for Carlton TV. None of this should debar a man from leading his country, we can't all be Churchills. It's just that, with al-Qaeda at large and a recession on the horizon, somehow you can't help thinking... Never mind. In a sense every new prime minister is inexperienced.

A difficulty for our young leaders of the future is that youth sells, which means that pressures to mature are less pressing than they were. When crossed in debate, Miliband easily reverts to adolescence, affecting an incredulous, nose-wrinkling, demotic “What?” (minus the “t”), prompting Jeremy Paxman to respond to the Foreign Secretary on one occasion: “Don't you patronise me.”

Then there are the lingering effects of school. If I had received one of the end-of-term reading lists sent to Tory MPs, including books by my leader's school chums, I would have had a fatherly word with the whips about the party's image in the adult world. Meanwhile, Boris Johnson claimed to have the biggest personal mandate in history after the London mayoral election. Actually 82 per cent preferred someone else or abstained. Which does not prevent Mr 18 Per Cent from proclaiming his plans for the capital a blueprint for the nation.

The most callow remark in Cabinet history must surely belong to Purnell who, as Secretary of State for Culture, assured us that the state of the arts in Britain was on a level with the Italian Renaissance: “I don't think it's an overstatement. It's exactly true.” Sad that after six months in the job our modern Medici had to hurry on to Work and Pensions, entrusting our contemporary Leonardos, Michelangelos and Palladios to the care of his successor Andy Burnham, a 38-year-old football fanatic.

We are used to a choice of personalities for the top job, but there too the range appears to be narrowing, as everyone takes the populist whip. Subservience to convention has become the hallmark of our strenuously relaxed, free-wheeling, be-yourself generation of “non-conformist” politicians. They dress down to express individuality, yet somehow they all look the same. Think of Churchill/Attlee, Wilson/ Douglas-Home, or Foot/Thatcher. Then think of Miliband/Cameron, or better still Cameron/Clegg.

Compliance with the commonplace and a lack of distinctiveness are striking, from their inconstant environmentalism to their choice in music. Past leaders liked classical, jazz, pop or, quite often, none at all. Now they're rockers to a man, and applauded for it. (Envy speaks a little here - I used to be a jazz drummer, but it never helped me.) Which would have the insouciance of Donald Dewar who, asked the names of the Spice Girls, replied: “I don't know and I don't care.”?

Politically their views are also of a muchness. A Cameron/Miliband/ Clegg coalition would have fewer internal strains than James Callaghan's last Cabinet (Tony Benn, David Owen) or the early Thatcher's (Sir Ian Gilmour, Norman Tebbit). So are our most likely lads men without qualities? I wouldn't go that far, but when they are so untested by life, who can tell? Maybe what they lose in personality they will gain in competence? In office, as in war, people grow up quickly. We must hope so.

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