People who dash off letters to 10 Downing Street should be warned. They may get more than they bargained for.

Complaints, queries and commendations — written about anything from benefits and bus services to the weather — normally receive a polite letter of reply on behalf of the Prime Minister, signed by an official.

But some of them, perhaps as many as two dozen a week, prompt a personal call, and the distinctive gravelly baritone of Gordon Brown.

The listening Prime Minister, as he has promised to be, is taking his pledge very seriously after several maulings in the polls.

Mr Brown, an inveterate reader and writer, is known to take a particular interest in almost everything that goes on in No 10, or comes into it. And sometimes, it was revealed yesterday, he asks the No 10 switchboard to get his correspondents on the phone.

The telephonist will call the number, say they have the Prime Minister on the phone and after the shocked listener has composed himself or herself, Mr Brown will be put through. “It’s Gordon Brown here,” he will say. “I was interested in your letter/e-mail . . .” and a conversation, often of several minutes, will ensue.

Most of Mr Brown’s calls or personal correspondence are with ordinary members of the public. But last week he swiftly sent off a letter to John Terry, the Chelsea captain, whom the nation watched weeping after he missed the penalty that would have given his team Champions League victory in Moscow.

Mr Brown’s occasional habit of calling the public was exposed in PR Week, now a “must read” for politicos after the appointment of Stephen Carter, the former chief executive of Ofcom, as Mr Brown’s strategy and communications chief. Several other public relations experts have moved into 10 Downing Street in his wake.

The magazine suggested that Mr Brown’s “cold-calling” of members of the public was the brainchild of Mr Carter, intended to “humanise the Prime Minister as his popularity continues to wane . . . The move is an attempt to spread positive word of mouth for the Prime Minister, especially in the regions.”

However, Mr Brown will be treading a fine line in his public conversations. Information experts said that he should be mindful of data protection rules when he rings up voters — while it is perfectly legal to call members of the public to ask how they will vote, the promotion of Labour policies could leave the Prime Minister caught by the rules governing marketing.

Mr Brown is not allowed to ring anybody who has signed up to the Telephone Preference Service, which is intended to exempt those people from receiving cold calls. A stray call or two will not excite the attention of the Information Commissioner, but several breaches will result in an enforcement notice being sent out.

However, Mr Brown is unlikely to fall foul of a tele-marketing ASBO. His new tactic has been tried and tested by politicians in the past, and can be traced back to Jimmy Carter’s 1976 US presidential campaign.

The PR Week claims about Mr Brown infuriated Downing Street officials, who insisted that the Prime Minister had regularly called members of the public and that it was also a practice he followed when Chancellor.

“He will often see personal things in these letters and just ask to make a call,” a senior aide said. “The response of most people when told that the Prime Minister is on the phone is, ‘You’ve got to be kidding’.”

It was known that Mr Brown often called the bereaved families of servicemen who had lost their lives in Iraq or Afghanistan but aides say that Mr Brown has never wanted to make a public issue of the fact that he will call up Joe Public occasionally.

No 10 denied a specific claim in the magazine that Mr Brown had, without thinking, once called someone at 6am.

Want to get something off your chest? Go to www.number-10.gov.uk At top of page , go to Prime Minister, click contact and follow instructions

When it’s good to talk . . .

— First ensure that it is the real Gordon Brown and not some pale imitation, such as Ed Balls. Ask if postneoclassical endogenous growth theory entails a thoroughgoing reform of Britain’s R&D subsidy framework. This is, of course, a trick question

— Bear in mind that it is highly unlikely that anyone would wish to pretend to be Gordon Brown

— He is rumoured to break handsets in sudden bouts of phone rage. Should the line go dead, ask yourself whether you may have mentioned Crewe & Nantwich or the 10p tax band

— Topics of conversation include: fuel prices and should you abandon plans to buy a diesel, nuclear power, the early work of the Bee Gees, courage, prudence, Britain’s sustained period of economic growth, your pain and whether or not he can feel it

. . . and when you’d rather not

— Unplug your telephone between 1am and 6am Read aloud into the receiver extracts from Cherie Blair’s autobiography

— If the Prime Minister calls while you are at work, answer every question with the words: “I’m getting on with the job”

— Interrupt his opening with the words: “I have listened and I have learnt.” Then hang up

— Tell him how much you enjoyed “that Times column by that Matthew Paris fellow”

— Inform him that the conversation is being recorded for training purposes

— Tell him that whatever he says you do not believe the two of you can reach a progressive consensus

— Ask if Scotland is really part of Britain

— Say “I'm so glad you rang. I’ve been meaning to tell you how much you remind me of that John Major chap”

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