Listen carefully to Labour-leaners and floating voters and you’ll hear remarkable unanimity. They want a leader who will pursue reformist, modernist policies . . . like Tony Blair. They want a leader with charm, charisma, and an ability to speak from the heart rather than a speechwriter’s notes . . . like Tony Blair. Most of all, they want a leader who understands their day-to-day hopes and fears and reflects that awareness in what they try to do . . . again, like Tony Blair.

They just don’t want Tony Blair.

This contradiction was evident last week when I sat down with a group of such Labour-leaners and floating voters. They were each issued with a “people meter”, a hand-held computerised device that allows the holder to turn a dial back and forth as he or she listens to a speech or presentation.

As a pollster I’ve used the “people meter” in more than 400 sessions in a dozen countries and I think you’d be hard-pressed to find a more accurate way of assessing whether a particular politician is likely to attract an individual’s vote. The meter allows the pollster to record voters’ reactions on a second by second basis as they turn the dial to indicate whether they would vote for the politician on the basis of what they are saying at this very moment — or not.

If the voters I talked to (for BBC’s Newsnight) had used their “people meters” to react to Blair’s conference speech I am convinced at least half would have wanted him to reconsider his decision to leave.

Blair’s effortless delivery showed why he was three times elected to lead the country. To quote a James Bond theme, nobody does it better.

So great has Blair’s influence on political communication been, incidentally, that it is not just his would-be successors who will have to emulate his fluent speaking style. A year ago I worked with a group of Conservative-leaners and floating voters in the run-up to the Tory leadership contest. From that session the message emerged — “it’s time for a change” — and David Cameron best personified the attributes and characteristics of change.

At the time Cameron was barely a blip in the national polls but he rose above his better known competitors primarily because he reminded voters of a younger, fresher, more conservative . . . Tony Blair.

Labour has reached a critical juncture in its history. The approaching leadership race is more than a battle of personalities between would-be prime ministers. When the party faithful cast their votes some time next year they will be declaring to the nation whether Labour will continue in step with the forward-looking British electorate or marching backwards in time.

In the past weeks a number of Labour-leaning columnists have laid out the case for why Gordon Brown should be the next leader of Labour. But what you never hear is why he will be the next elected prime minister.

Interestingly, the voters in my session came out clearly in favour of John Reid, not Gordon Brown, as the next party leader. Polly Toynbee, writing in The Guardian last week, suggested dismissively that it was just because of the “hesitant” Brown response to a reporter’s questions about his role in the leadership coup and “the full-on harangue” Reid recently unleashed against the legal system.

Actually, she’s correct — but she ignores the significance in her conclusion. You be the judge. Here’s exactly what Reid said that made the Labour-leaning voters sit up in their seats, nod their heads and cheer: “Any system which allows foreign prisoners back on our street without even considering deportation has something wrong with it — full stop. No qualifications. A court judgment that puts the human rights of foreign prisoners ahead of the right to safety of UK citizens is wrong — full stop. No qualifications. A Parole Board decision that emphasises the rights of a convicted murderer over the rights and safety of his potential victims is tragically, murderously wrong — full stop.”

The “people meters” soared, and it was the single best-received language of the evening. To Toynbee that was a full-on harangue. But to Labour-leaners and floating voters it was good plain common sense. Could you imagine Brown speaking with such emotional clarity? Could you imagine Brown with such steely determination?