But one of Khan’s other successes has been to convince the electorate that he is a man of the people, despite the fact that he and many of his inner circle come from the same privileged elite they accuse of betraying the country. Khan went to Aitchison College, the Eton of Pakistan, before moving to the UK and studying at Oxford. His foreign affairs spokesman, Shah Mehmood Qureshi, also attended Aitchison.

When I visit Qureshi in his beautifully furnished home in Lahore, there is a history of Aitchison College on the table in his study and a photograph of Qureshi and other students (including the Conservative politician Bernard Jenkin) at Corpus Christi College, Cambridge, hanging on the wall. Qureshi comes from a long line of saints, scholars, politicians and landowners, but became a populist hero in 2011 when he quit as Pakistan’s Foreign Minister after Zardari pushed to grant immunity to a CIA agent, who had shot dead two unarmed Pakistanis in Lahore.

“My view was that he was not a diplomat as the Americans claimed,” Qureshi tells me. “Mr Zardari was of the view that he should be granted diplomatic immunity.” As soon as he had resigned, he was immediately approached by PML-N chief Nawaz Sharif. “He said words to the effect that I can’t see a better person than you to be Foreign Minister of Pakistan,” says Qureshi. But he turned down the offer.

“Frankly, the way I saw things deteriorate, I am convinced that this country cannot be run on the basis that it has been run. Structural changes have to be made. For the first time, I feel people are genuinely worried about the future. I feel serious concerns about an existential threat to this country. We are collapsing from within,” maintained Qureshi.

As well as a failing economy, Pakistan is plagued with chronic power shortages, an epidemic of local insurgencies and sectarian violence on a terrifying scale. And stable government is absolutely crucial over the next 12 months as British and American troops prepare to pull out of Afghanistan. A collapse of the Pakistan state raises unimaginable nightmares. The entire region could be dragged into a set of conflicts, even more terrible than the civil war that engulfed Afghanistan after the collapse of Soviet rule in the 90s. It would also present new opportunities for terror groups and crime syndicates from Afghanistan, trafficking drugs, weapons and people to the West. The danger of political instability are all the graver since Pakistan, like neighbouring India, holds nuclear weapons.

For Qureshi, PTI is the only party capable of guarding against these dangers. And Umar is specific about the “structural changes” required. The PTI, he says, would break up Pakistan’s centralised state. “We need to bring power down to the grass roots level,” he tells me. “In terms of governance, we want to take it back to where it was when Jinnah was Governor General.”

Mohammad Ali Jinnah, the founder of Pakistan, died in 1948, a year after Pakistan gained its independence. Therefore, Umar is effectively saying that he wants Pakistan’s system of government to return to the high standards of probity and efficiency it enjoyed at the time of British rule. One of the common themes among Khan’s inner circle is a despair at the existing two-party system and its failure to solve Pakistan’s problems.

Before I leave Pakistan, I conducted one final interview. It is with Khan’s political strategist, Javed Hashmi, who, I noticed, was treated with the most deference by Khan at the private meeting I attended. One of the country’s best-known public figures, Hashmi has been involved in politics since the 60s, when, as a student agitator, he was imprisoned and tortured by dictator Ayub Khan. In all, he has endured five long terms of imprisonment, of which the most recent was a long stretch courtesy of President Pervez Musharraf, who stepped down as Pakistan’s military ruler five years ago. Hashmi was accused of treason after criticising military rule.

Why has he joined hands with Khan?

“Bringing democracy to this country and fighting against corrupt leaders is my agenda as well as his,” Hashmi tells me. “People see Nawaz Sharif, they see Zardari, they see nothing has changed. For 10 years, Imran has struggled and worked. He is saying the right things, I must follow him.”

Just over 40 years ago, most people dismissed the chances of Bhutto when his newly-formed PPP ran in the 1970 national elections. Defying all the odds, his party caught the national mood, and swept home in West Pakistan. Could Imran Khan, the sporting legend famous for snatching victory from the jaws of defeat, be about to repeat history? It is a real possibility.

The writer is a British journalist and political commentator. This article has been reprinted from the Telegraph.