Tony Blair has suggested he did not enjoy his time in Downing Street due to the "huge" responsibilities of the office and the "massive scrutiny" on his family.
The ex-Labour leader was swept to power in 1997 after winning a huge 179-seat majority, bringing to an end 18 years of Conservative government. He would go on to win the next two elections before being succeeded by his chancellor, Gordon Brown, in 2007.
In an interview with BBC Radio 4 to promote a new series on how the office has changed over the past 300 years, Mr Blair said it was "crazy" that the experience required for the top job was "nugatory".
Mr Blair was first elected as the MP for Islington in 1983 and served as a shadow minister before becoming Labour leader in 1994 and prime minister three years later. But there is no official training given to those entering No 10.
The historian Sir Anthony Seldon has previously suggested Mr Blair's most successful period of governing came in the latter years of his premiership, after the controversial decision to join the US's war with Iraq – a sentiment echoed by the former prime minister in his interview.
"The paradox is that you start at your most popular and least capable and you end at your least popular and most capable," he said.
Overall, Mr Blair said, the weight of the office and the pressures that came with it sometimes meant the job was not enjoyable.
"I don't think I did enjoy the job because the responsibility is so huge," he said. "Every day you're making decisions and every day you're under massive scrutiny as is your family. So I didn't know if I enjoyed it."
He also compared his experience of becoming prime minister to that of a fan being appointed as manager of Manchester United.
"The first job I ever had in government was prime minister," he said. "I use the analogy of a football team. "If you're looking for the new coach of Manchester United and [say], 'I tell you what we're going to find the most enthusiastic and persuasive fan we can find and put him in charge of the team’, people would say you're insane."
Radio 4 also spoke with former prime ministers David Cameron and Sir John Major, as well as to the current officeholder Boris Johnson.
Mr Johnson told the BBC: “The great thing about being in Number 10, as I think probably any prime minister has found, is that it’s a job that is brilliantly supported by a massive team of people who have all evolved over hundreds of years into what is a big department of state now.
“And what you’ve got is an 18th-century townhouse, rather beautiful.
“So this is an incredible institution that has evolved over time into this extraordinary centre of a G7 economy.”
The first of three programmes in the series will air on BBC Radio 4 at 11 am on Friday 2 April.
Additional reporting by Press Association
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