John Humphrys: He's started so he'll finish

A reprimand for 'bias' seems to have done little to undermine the status of one of our most eminent broadcasters

The time will come when John Humphrys no longer needs to set his three alarm clocks for 3.59am, when he can stand down the loyal taxi drivers who transport him through pre-dawn London streets to the studio, and when the focus of his working day is not an 8.10am confrontation with a senior politician.

But that day is no closer in spite of the fact that Humphrys, who will turn 70 this month, has this week been the subject of a quarrel remarkable even in the tumultuous career of Britain's most pugnacious broadcaster. The uproar came after Future of Welfare, a BBC2 documentary Humphrys presented after returning to Splott, the Cardiff neighbourhood where he grew up, was held by the BBC Trust to have breached editorial standards on partiality.

The presenter immediately found himself elevated to martyr status by the Tory press. "BBC attacks Humphrys for telling the truth on welfare," said a splash headline in the Daily Mail. "Humphrys 'a victim of BBC Left-wing bias'," said the front page of The Daily Telegraph, quoting Work and Pensions Secretary Iain Duncan Smith, who said of the broadcaster: "I don't know anybody who thinks he is in any way biased."

Such was the uproar that the BBC's governing body felt the need to respond. BBC trustee Alison Hastings noted that the ruling was not a criticism of the documentary's presenter but the programme's lack of supporting statistical information. For once, the silver-haired Welshman was not a direct participant in the heated exchanges. But the upshot is that his place on one of the central plinths in the national discourse is guaranteed – probably for as long as he wants it.

Who could fire John Humphrys now? Just a few months ago he delivered one of the most memorable interviews broadcast on BBC radio when he effectively sealed the fate of his own Director-General George Entwistle by exposing his failure to grasp the gravity of the Savile and McAlpine crises. "So you've no natural curiosity?" Humphrys asked his boss. "You wait for someone to come along and say: 'Excuse me, director-general, but this is happening, you might be interested.' You don't do what everyone else in the country does – read newspapers, listen to everything that's going on…"

The interview helped to ensure that Humphrys was named Radio Journalist of the Year at this year's Sony awards, another addition to his sizeable trophy cabinet.

Last month, the new director-general Tony Hall tweaked the presenting line-up of the BBC Radio 4 Today programme, for which Humphrys began working 26 years ago. Another female voice (Mishal Husain) is being introduced. It is James Naughtie – Humphrys's long-standing colleague and eight years his junior – who will make way to spend 2014 covering the Scottish independence referendum. It is inconceivable that a D-G would lay a finger on Humphrys after the Entwistle episode, and at a time when the BBC is already fighting interference in its affairs by MPs.

Most of the past political attacks on Humphrys have come from the left. Labour's director of communications Dave Hill once spoke publicly of the "John Humphrys problem". However, the Daily Express – no doubt to the great annoyance of the journalist – once ran a headline: "Humphrys for Prime Minister".

In 2005, a tape of one of his after-dinner speeches was leaked to The Times by a former Labour spin doctor, Tim Allan. The humorous address mocked government figures including John Prescott and Peter Mandelson, but the paper's suggestion that the presenter had implied that Labour's leaders were liars was attacked by Humphrys as a "gross misrepresentation". The BBC described the comments as "misguided" but did not ban Humphrys (who is a freelance) from the lucrative after-dinner circuit.

His voting habits, along with his salary (said to be £375,000 after a £75,000 reduction to reflect straitened times at the BBC), are things Humphrys will never discuss. Friends note that although he is quickly riled by compensation culture he is also the founder of the Kitchen Table Charities Trust, which funnels money to children in Africa. And, to support Mr Duncan Smith's point about lack of bias, he once interrupted the Tory Chancellor of the Exchequer Kenneth Clarke 30 times in a single interview. Humphrys is a fearsome adversary for politicians of all hues.

And, generally speaking, the public appears to like what he does. The BBC announced this week that Today's audience has grown by 200,000 in the past year to nearly seven million, helping Radio 4 to record ratings.

He is famously irascible. This is no doubt partly explained by his early starts – but he also needs to feed an apparently insatiable hunger for life, aptly reflected in the fact that he also presents Mastermind on BBC TV. He is a passionate reader and classical music fan who wishes he could master the cello. He goes for long walks in the Welsh countryside, climbed Mount Kilimanjaro and for decades had a farm in Carmarthenshire despite the "enormous strain". He has written a book with his son Christopher about their exhausting attempts to convert a derelict Greek cottage. Other books concern his search for God and his frustration at the mangling of the English language. He has a younger girlfriend (Guardian journalist Catherine Bennett) and a 13-year-old son from a previous relationship, in addition to his two grown-up children.

Since he left school in Cardiff at the age of 15 to become a newspaper journalist, Humphrys has been in a hurry. He joined the BBC in 1966 and within five years was Washington correspondent, covering Richard Nixon's resignation. Many remember him as the face of the Nine O'Clock News, though he found the role insufficiently taxing and moved to Today, the programme with which his name is now synonymous. He has been a staunch defender of the programme, speaking out to this newspaper in 2007 when it was threatened with cuts and suggesting that the BBC's new digital television channels ought to be axed first.

His reputation has survived his involvement in the infamous 6.07am two-way exchange on the Iraq war with reporter Andrew Gilligan, which led to the devastating Hutton Report in 2004. While the then Director- General Greg Dyke, chairman Gavyn Davies and Gilligan all departed, Humphrys has remained. He always said it was his ambition to match Today stalwart Brian Redhead's record of 20 years on the programme, but he passed that milestone six years ago.

During recent years he claims to have mellowed – "I'm much more inclined to laugh at something that's absurd rather than lose my temper" – and this summer he went camping at Glastonbury for the first time, broadcasting Today live from the festival and showing a softer side as he interviewed Mick Jagger. No mud stuck to him, and it seems unlikely that any criticism will either.

A life in brief

Born John Humphrys, 17 August 1943, Cardiff, Wales.

Family Two children with former wife Edna Wilding. A son with former partner Valerie Sanderson. Now in a relationship with the journalist Catherine Bennett.

Education Left Cardiff High School at 15 to work in newspapers.

Career Joined the BBC as a reporter in 1966, became a foreign correspondent. Was the BBC's first full-time US television correspondent for six years before relocating to South Africa in 1977. Returned to the UK in 1980 as a diplomatic correspondent, before presenting BBC1's Nine O'clock News. Joined Radio 4's Today programme in 1987.

He says "Language is about subtlety and nuance. It is power and it is potent."

They say "John Humphrys is a robust interviewer, one of the best in British broadcasting today." Stephen Mitchell, ex-head of BBC radio news.