Sir Tony Blair’s wife has claimed her husband had ‘lost contact with reality’ by the time he resigned as prime minister nearly two decades ago.

Speaking in a new Channel 4 documentary, Cherie Blair has reflected on Sir Tony leaving Downing Street in 2007 after ten years leading the country.

Mrs Blair said: ‘Your skill as a politician is about knowing about the people and living with the people and understanding what the people want.

‘Ten years of living in the goldfish bowl, you kind of lose contact with reality.’

She added that Sir Tony – who is the longest-serving Labour prime minister in British history – ‘can make people think they hear what they want to hear’.

The three-part series also hears from Sir Tony himself, who says: ‘One of the things you learn is that ultimately you sit in the seat. You’ve got to take the decision.’

Sir Tony’s grown-up children, Euan, Kathryn and Leo, feature in the documentary – airing next Tuesday – along with his former spin doctor Alastair Campbell.

Mr Campbell talks about a moment when he found Sir Tony at his desk in No10 late at night following the invasion of Iraq in March 2003.

Sir Tony Blair’s wife Cherie Blair is interviewed in ‘The Tony Blair Story’ airing on Channel 4

Tony Blair – the longest-serving Labour prime minister in British history – with his family as they leave Downing Street for the final time in 2007

Cherie Blair talks to series director Michael Waldman in the new Channel 4 documentary

He says: ‘It was one of those moments when I wished I could paint. It was an absolute portrait in the isolation of power.’

Mr Campbell adds of Sir Tony: ‘He had real energy and restlessness.’

A trailer for the documentary released today also features clips from interviews with broadcaster Andrew Neil and former chancellor George Osborne.

Mr Neil is heard speaking about the ‘whole obsession with spin’, while a clip from Mr Osborne says: ‘People lost faith in what government was telling them.’

Former Labour leader Jeremy Corbyn also says: ‘I think he’s a man in denial.’

The clip concludes with the narrator saying the series has ‘the full account in his words and featuring those closest to him’, and Sir Tony says: ‘Make your own judgment.’

Series director Michael Waldman wrote in the Radio Times today: ‘His self-assurance rarely cracks, even when interrogated about what many view as his gravest mistake, the invasion of Iraq.

Sir Tony Blair is also interviewed in the new documentary which looks at his rise to power

Sir Tony Blair speaks to director Michael Waldman for the new Channel 4 programme

‘Despite this conviction, what emerges is a level of emotion and psychological introspection that’s rarely been seen on camera.’

He added that there was ‘no doubt power changes a person’, and Mrs Blair’s reflections on her husband leaving office in 2007 were ‘words that, perhaps, anyone in power should heed’.

The documentary will look at how Sir Tony took over as Labour leader in 1994 following the sudden death of John Smith – and how he talked close ally Gordon Brown out of running.

It will cover his landslide election victory in 1997, his work in Northern Ireland and Kosovo and the relationship he built with President George W Bush amid the 9/11 attacks and military action in Iraq and Afghanistan.

Former president Bill Clinton and Condoleezza Rice appear in the documentary too, which also looks at how Sir Tony was forced out by Labour in 2007 and replaced by Mr Brown.

‘The Tony Blair Story’ airs on Channel 4 next Tuesday at 9pm