So, four years after Sir Robin Day reluctantly stepped down from Question Time, you've got the job you so wanted. Tonight we shall see your first appearance as its presenter.

Patrician figures such as yourself, head of media's most respected dynasty, probably don't take kindly to advice. You were born to authority and have chosen to pursue it. Your father, Richard Dimbleby, was described as 'the voice of England' after his magnificent commentary for Winston Churchill's state funeral. The magisterial comes easily to you. You belong to Brooks's Club, you dance with princesses and marchionesses. As James Naughtie said of you recently: 'David is very much a guy who moves in fairly exotic financial and cultural circles.'

All the same, you can't be reminded too often that Question Time is not about giving a voice to the politicians and those set in authority over us. They get plenty of chances to speak, although, as we have now discovered, no one actually believes what they say. But Question Time's unique selling point is that it gives a voice to the public, as represented by each Thursday's invited audience. Ordinary men and women get a chance to question cabinet ministers, live, on air: your prime function will be to help them to do it effectively.

It may not be easy for a man such as yourself, on terms of close friendship with Douros, Waldegraves and Guinnesses, to identify with the ordinary folk in the audience rather than the grandees on the platform, but make no mistake: that's your job. Some 4.5 million of us watch Question Time, hoping for a repeat of that marvellous moment in 1983 on Nationwide when Mrs Gould, Ordinary Housewife, asked Mrs Thatcher, Prime Minister triumphans, why she had ordered the Belgrano to be sunk when the ship was outside and sailing away from the exclusion zone, and wouldn't be fobbed off. That's what we hope for: a chance to see the politicians trounced, at the very least rattled.

The belief that you are 'good with audiences' is the main reason why the job went to you rather than young Paxman, a man without any discernible sympathy for politicians and no inclination to socialise with them. Trouble is, as he apparently demonstrated in his audition (oops, sorry, we call it a pilot, don't we: chaps as eminent as you and Jeremy don't audition), he hasn't a lot more sympathy for the sometimes incoherent and inarticulate mutterings of audiences, either.

It's hard for a man such as yourself, who will be paid a rumoured half a million pounds a year by the BBC, to say nothing of that nice little earner in the form of your newspaper group, Dimbleby & Sons, to identify with people whose wages may be closer to pounds 250 a week. But they have a rarely exercised democratic right to cross-question the Chancellor of the Exchequer, and it's your job to see that he doesn't wriggle off their hook. You won't let the ordinary folk down, David, will you?

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