Youth is not everything in politics, but it has a lot going for it under Mr Blair

Come to think of it, a spirited young MP called Tam Dalyell was on the first step of the ministerial ladder by the age of 3

Tam Dalyell is invariably worth listening to. Yesterday, he spoke for many in his party when he lamented the speed with which the latest reshuffle has propelled two of the newest and youngest MPs – David Miliband and David Lammy – into high-profile ministerial posts, and seen the promotion of some notably young ministers. Those who had "laboured in the parliamentary vineyard for a long time" deserved better consideration; the danger was that MPs in their forties and fifties would lose heart from not being given the chance to show what they could do in government office.

That Tony Blair is instinctively a generation-skipper isn't much in doubt. He was much more reluctant than he need or should have been, back in 1997, to appoint some of the brightest of the older MPs to ministerial office, particularly since the Government – from the Prime Minister down – was almost wholly lacking in ministerial experience. To take a few random examples, Giles Radice, a proto-Blairite who had been a shadow Education Secretary, would almost certainly have been an excellent first Minister for Europe in the Foreign Office. Denzil Davies had had a turbulent history under Neil Kinnock, but as a former Treasury minister with one of the best minds in his era, he would surely have enriched that first administration. Neither was called to office.

Lord Rooker, now 60, is, by contrast, a first-class Minister of State, honourably swapped in last week's reshuffle with Lord Falconer of Thoroton. It's hard to see what has stopped him becoming a member of the Cabinet, if not his relative age – other than that he came to political maturity in the Callaghan years. It's striking that the only Cabinet Minister in the House of Commons who is over 60, John Prescott, not only has an identifiable political constituency but is also the one Labour man, apart from Mr Blair himself, directly elected to office by the entire party.

Yet previous political generations would have regarded 64 as a wholly unexceptional age to hold high office. There was something of the year zero in that 1997 administration. Where Tony Blair reached beyond the elected Shadow Cabinet, he mainly did so to a younger generation, as if he feared contamination by those who had known previous Labour governments inside out. So Mr Dalyell and his colleague Donald Anderson have a real point.

Mr Dalyell was no doubt also right yesterday to remark that the strange case of Michael Wills, dismissed as a minister on Wednesday and reappointed on Friday, was unprecedented. This is highly embarrassing for the Government – and would have been a great deal more so if the voting public weren't a little more preoccupied with the World Cup and the golden jubilee – and seems to have been a little messier than a straight fight in which Gordon Brown went into meltdown because one of his men had been sacked by Mr Blair.

It may well be that Mr Wills had raised some hackles by reopening a risky IT decision in the Lord Chancellor's Department, although he was probably right to do so. It's true, too, that he is very much a Brown man. But without any particular personal animosity to Mr Wills, Mr Blair seems to have decided that he needed his job to make way for the former public health minister Yvette Cooper, also close to the Chancellor. He offered Mr Wills an advisory role outside the ministeriat instead. Mr Wills then managed to negotiate this, no doubt after turning to Mr Brown for advice, into an (unpaid) job at the Home Office.

But Mr Dalyell will know better than most that precedent is not on his side when it comes to his distress at the appointment of very young and, in parliamentary terms, inexperienced ministers. His case against Mr Miliband's appointment to the middle-ranking job of Minister for Schools is not so much because of his age (he is 36, while Mr Lammy, who is clearly a potential star, is only 29), but because he only came into the Commons last year. But Harold Wilson was elected in July 1945 at the age of 29 and became a minister just one month later. Two years later, at the age of 31, he was in the Cabinet. David Owen was a minister by the age of 30. R A Butler, Ted Rowlands, and more recently Ann Taylor all held some form of government office at the age of 29. Come to think of it, a spirited young MP called Tam Dalyell was on the first step of the ministerial ladder by the age of 32; as Parliamentary Private Secretary and close confidante to Richard Crossman throughout the 1964-70 government, in a much more turbulent period than the present one, he arguably had more responsibility than several ministers.

Which is as it should be. For just as it is wrong not to appoint good men and women because they are over 50, so it would be equally wrong not to appoint others because they are judged too young or inexperienced by some quaint yardstick of parliamentary seniority. Of course there needs to be a balance; of course there are problems of maintaining motivation in the middle ranks of MPs. But the accusation levelled in the past at successive governments – including this one – is that they have used too many ministerial appointments rather than too few, merely for reasons of ministerial patronage.

In future it may be that more backbench MPs will see that there is an equally important career away from the greasy pole – one of scrutiny and holding the executive to account. The clever, serious MP Chris Mullin, who is 54, and who left office voluntarily, may not be the last to discover that being chairman of a Select Committee carries more weight than being the junior minister for shuffling paperclips.

It isn't just that Mr Miliband had already held a senior position in government as head of the Downing Street policy unit. It isn't just that he is clever, which he certainly is. It's also that among the inner circle of New Labourites he is clearly identifiable as a "conviction politician". If the Government is remotely genuine about the overdue sentiments laid out in the spectacularly revisionist text by Peter Mandelson in the new preface to the book he co-wrote with Roger Liddle, The Blair Revolution – an end to spin, more action to remedy social inequality and a recommitment to education spending – then Mr Miliband is your man.

He doesn't, on the whole, do spin. He is on record with a recent and excoriating analysis of the Government's failure to address the scarring class divisions that mean that fewer than 1,000 students from the lowest two socioeconomic groups went to university last year. He has therefore set himself some high hurdles for his new job.

That, however, will make him all the more worth watching. Maybe he will fall flat on his face. But at 36, should he really wait his turn for this urgent task by spending more long nights on the Standing Committee on the Number Two Bill: Street Lighting in Rural Areas? I doubt that, deep down, Tam Dalyell, an instinctive and outstanding backbencher who became an MP at 30, really thinks so.

d.macintyre@independent.co.uk