They are the BBC’s “news rottweilers”, the aggressive interviewers and hosts who are popular with the public for refusing to let politicians get away with evasions or prerehearsed answers.

But the four attack dogs – John Humphrys, Jeremy Paxman, James Naughtie and David Dimbleby – are each nearing retirement, so the corporation has started a search to find their long-term replacements.

Executives say that none of the four is under pressure to leave, but there are concerns that their departures would create a void. “We need to think about this now, so a new generation is ready, particularly if they all retire in quick succession,” a well-placed BBC source said.

David Dimbleby, the presenter of Question Time, is 69, while John Humphrys, of the Radio 4 programme Today, is 64. Jeremy Paxman, who once asked Michael Howard the same question 12 times on Newsnight, is 57, while Humphrys’s colleague on Today, James Naughtie, is the youngest of the quartet at 55.

The requirement for the BBC to develop new talent has led to Emily Maitlis, 37, being moved to Newsnight, and Evan Davis, 45, the corporation’s economics editor, moving to Today in April – although neither is known for an aggressive style of questioning.

Among those regarded as potential interrogators are Justin Webb, the BBC’s Washington correspondent, and his predecessor Matt Frei, who presents news bulletins on the BBC America channel. Nick Robinson, the political editor, is well thought of as an interviewer, although it would be difficult to move him from his high-profile role.

The BBC faces a dilemma in that it is difficult for its younger journalists to hone their techniques outside the forums of Today, Newsnightand Question Time, yet the current incumbents have held their posts for a generation – Paxman has hosted Newsnight since 1989, and Humphrys dominated Today from soon after his appointment in 1987. David Dimbleby, who has anchored election coverage since 1979, took over from Sir Robin Day to present Question Time in 1994.

Mark Thompson, the BBC Director-General, defended their tough style of questioning last month. In a speech on trust in public life, he argued that public confidence in politicians would not be restored by a softer approach. “I don’t believe that the public want to see less rigour in our questioning of politicians and other public figures: if anything, they want to see more,” he said.

Leaders of the pack

David Dimbleby, 69
Rottweiler rating 7/10
Last symbol of the old-style, patrician BBC. Dimbleby controversies are rare but he lost control of a Question Time after 9/11

John Humphrys, 64
Rottweiler rating 9/10
Able to put the most practised of politicians off balance but his style means he is not good with members of the public. Rapped on the knuckles in 2005 for making fun of Labour ministers

Jeremy Paxman, 57
Rottweiler rating 9/10
Repeatedly asked Michael Howard if he had threatened to overrule Derek Lewis, who ran the Prison Service, over the sacking of a prison governor. Often looks bored in interviews

James Naughtie, 55
Rottweiler rating 5/10
More sympathetic than his Today partner. Accused of Labour sympathies when he referred to the party as “we” during an interview with Ed Balls

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