The attacks are coded, but not too cleverly. We do not need the Enigma machine to work out what is meant. When complaints bubble up from "real Labour" MPs, or "traditional" activists, or erstwhile party luminaries with seats in the House of Lords, their target is clear. They make ritual noises about the need to adapt to the modern world. They admit that not everything was perfect before 1994. But when they say that the government ignores its core supporters, that it should be more mindful of Labour's long-standing principles, and that ideology should be restored to British politics, what they are really saying is: down with Blair.
Nobody, yet, has the gumption to say that Labour should have a different leader. But the critics propose measures that they know Tony Blair would never countenance. Were they honest, they would mount their charge directly. They would say that Labour would have won the last election easily under any half-competent leader, that Blair has fashioned a disgracefully right-wing government, that millions of voters have grown disillusioned, and that Labour would do better under a new leader who reconnected the party to its radical roots.
Would they have a case? Think back not to 1997, but to September 1993, ten months before Blair became party leader. It is a year after John Major's government was humbled by Black Wednesday. The Tories stand accused of breaking one of their main election promises by putting up taxes. They lag 20 points behind Labour in the polls. Many people think that Labour is on the way to a big election victory.
One member of Labour's shadow cabinet thinks otherwise. Like today's critics, he writes a thinly veiled attack on the party leader. In that month's Fabian Review, he condemns what he calls "the 'one more heave' school of thought - the tendency that dare not speak its name". This tendency, he says, believes that Labour should take no risks while it waits for victory to fall into its lap. The writer disagrees. He argues for a new kind of radicalism based on "new economic opportunity, not engaged in a battle for territory between the private and public sector". Without such a transformation in Labour's appeal, "the result will be that the anti-Tory vote goes to the Liberal Democrats as much as, and in some areas more than, to Labour".
That was Tony Blair, giving vent to his private frustration with what he regarded as John Smith's excessively cautious leadership. Nobody could have foreseen that, within a year, Blair would have the chance to put his theories into action - and that the effect would be to vindicate his analysis completely.
Gallup's tracking surveys for the Daily Telegraph tell the story. In June, July and August 1992, the three months before Black Wednesday, average support for the three main parties was: Labour 42 per cent, Conservative 39 per cent, Lib Dems 15 per cent. In the same three months a year later, as Blair grew disillusioned with Smith's leadership, the figures were: Labour 44 per cent, Conservative 24 per cent, Lib Dems 26 per cent. Tory support had collapsed, but almost entirely to the benefit of the Lib Dems, rather than Labour.
Now look at the same summer months two years later. It is 1995. Blair has been Labour leader for a year. He has proclaimed the case for "new Labour" and persuaded his party to drop Clause Four. Labour's support is up 13 points to 57 per cent, while the Tories languish on 24 per cent. The real victims of Blair's first year have been the Lib Dems, down 12 points to 14 per cent.
What those figures show is that Blair succeeded where Smith had failed. He grabbed for Labour the lion's share of the ex-Tory vote. The Tories staged a partial recovery from their mid-term trough; and yet, when Labour won the general election in 1997, one of the most extraordinary features was the way it stormed so many of the Tories' middle-class suburban citadels. Stephen Twigg's victory over Michael Portillo was the most celebrated example. There were many others - such as Harrow, Wimbledon, Romford and Finchley in London, and the Conservative Party's remaining enclaves in and around Birmingham, Leeds, Bristol, Manchester, Cardiff, Edinburgh and Glasgow.
The importance of Labour appealing to middle-class voters cannot be overstated. In 1964, when Harold Wilson led the party to its first election victory for 14 years, only 29 per cent of the electorate belonged to the middle and professional social classes - the ABC1s; 71 per cent were working class, C2DE voters. A folk myth has evolved that Wilson seduced the middle class with his talk of the white heat of technology. But this is not true. The Tories swamped Labour among ABC1 voters by 66 per cent to 19 per cent. Wilson's victory relied on Labour's domination of the C2DE vote, where the party beat the Tories by 57 per cent to 32 per cent.
Since those days, the social character of Britain has been transformed. The country is divided 50-50 between ABC1 and C2DE voters. No party can hope to win outright without a fair amount of political cross-dressing - either the Tories must win over a large number of C2DE voters (as Margaret Thatcher did) or Labour must win the confidence of the middle classes.
In 1997, Blair repeated Wilson's achievement of beating the Tories by almost two to one among C2DE voters - and far exceeded anything Wilson ever managed, by reducing the Tories' advantage among the richest, AB voters to just ten points, and achieving parity among C1 voters. Since 1997, that trend has continued. According to MORI's surveys from the first half of this year, Labour has slightly increased its support among C2DE voters, and achieved further sizeable swings in its favour among the middle classes. Labour has achieved a sustained lead among AB voters for the first time in its history, and routinely holds a double-digit lead among C1s.
That was the vital ingredient of Labour's unprecedented achievement in retaining a substantial lead over the Tories throughout its first 40 months in office. No previous government can boast such a record. Recent polls, showing Labour losing its lead during the petrol crisis, do not fundamentally alter the analysis. Indeed, they confirm one of Blair's consistent messages to his own activists: that Middle Britain is likely to revolt if taxes go too high. Whatever the long-term solution to the crisis, it is unlikely to include another upward ratchet in tax-and-spend.
It's not just a matter of psephology. One consequence of Blair's achievement is a sharp reduction in class divisions in British politics. Previous Labour leaders have sought to build one-nation politics; Blair is the first to succeed.
To say that Labour needed Blair's reforms to achieve all this is not the same thing as saying the party still needs him. Could the party retain its appeal without him? Plainly, we will not know until it happens. Scientists are able to conduct controlled experiments; political scientists cannot, when the subject of their inquiry is a whole nation. However, that does not mean we can say nothing.
For a start, the fortunes of a post-Blair leader would depend on the circumstances of the succession. Were Blair to be overthrown by a rival bent on reverting to "original" Labour values, the effect might be to enthuse a large number of working-class voters who currently support the Tories, Lib Dems, Greens or nationalists. But would the numbers be large enough to offset the likely return of many middle-class voters to their traditional Tory home? And would the benefit be felt in the right places? Under our current electoral system - which party traditionalists say they favour - there is little point in building up even bigger majorities in Labour's inner-city heartlands when the price is losing support in the suburban marginals.
A trickier question is what might happen if Blair were to leave Downing Street at a time of his own choosing, and be succeeded by a leader of the same political cast of mind. This raises a number of imponderables. Does part of Blair's appeal to middle-class English families flow from his being a middle-class "Englishman" with four children? Would a (so far) childless Scot, such as Gordon Brown, or a working-class high achiever, such as David Blunkett, have the same appeal?
Their supporters say they would be able to enthuse traditional Labour supporters without alienating the party's middle-class converts. Perhaps. At the margin, there are arguments to be had about the precise nature of Labour's policies on direct versus indirect tax, welfare, redistribution and public services. But if Labour is to remain Britain's dominant party in the post-Blair era, whenever that begins, it cannot tear up new Labour's reforms and start again. The leadership's critics may say, or imply, that they want Blair without Blairism; in the long run, the far likelier prospect is that they will have Blairism without Blair.