It’s hard to think of Pakistan as a big country of warring factions when its entire leadership rotates through London, with the Dorchester Hotel the stage of choice.

Nawaz Sharif, the former prime minister, yesterday chose the Crystal Hall of the Dorchester to announce that he would make his “return to Pakistan, ending my exile” on Monday, September 10.

“It is to respond to the call of destiny, for the restoration of undiluted democracy in Pakistan,” he said, to a packed room of 200 journalists shouting questions in Urdu and English, the tops of the television tripods brushing the crystal fringes dangling from the perilously low ceilings.

He would land in Islamabad, the capital, he said, because that was where he was forced to leave almost eight years ago, when he was deposed by General Pervez Musharraf in a military coup. Then he would go by road to Lahore, the capital of the Punjab and the heart of his political base – that is, if he is not arrested on landing.

“Mr Musharraf sometimes says that the moment I return, he’ll bung me in,” said Sharif. “But he put me in jail before for months, in solitary confinement in a 16th-century fort. I was treated worse than a prisoner of war. I’m not scared.”

Sharif has spent most of the past eight years up the road from the Dorchester, brooding in a Victorian mansion flat opposite Selfridges, itself a breath of his own country transplanted into Mayfair, the dark stairwell and ironwork lift giving way to a hall filled with men in dark suits, pacing and watching the news from home on wide-screen television.

After years when Mr Sharif had seemed doomed to bitter and impotent denunciations of Musharraf, the news suddenly turned in his favour. On July 20 the Supreme Court, led by Chief Justice Iftikhar Chaudhry, who has directly challenged Musharraf’s legitimacy as President, ruled that Sharif has “an inalienable right to return and live in the country” as a citizen of Pakistan. But the court’s decision does not rule out the possibility that Musharraf would try to bring corruption charges against Sharif, leader of the Pakistan Muslim League, one of the two big parties.

Musharraf, himself a regular at the Dorchester (although he declines to be photographed against its heavy floral furnishings, as too effeminate), was championed by the US after September 11, 2001. But he lost its support this spring because of the clash with the courts and the suspicion that he is tolerating the Taleban resurgence in Afghanistan.

Yesterday, in a 17-minute declaration in Urdu, Sharif said that he and his brother Shahbaz, also a politician, would return together to make the “160 million people of Pakistan masters of their own destiny”. Urdu, often ornate and formal, resorts to English vocabulary for modern exigencies, and words such as “dictatorship” and “Army House” incongruously burst out of Sharif’s diatribe. Given Pakistan’s 32 years of military rule, it is perhaps not surprising that Urdu uses the English word for “democracy” but astonishing, given its feverish politics, that it does not have its own form of “floor-crossing and horsetrading”, a phrase Sharif spat out with contempt.

That referred to speculation that Benazir Bhutto, another former prime minister, leader of the Pakistan People’s Party, the other big party, and also an exile currently in London, might strike a power-sharing deal with Musharraf (breaking a pact a year ago with Sharif). Her talks with Musharraf have had the warm backing of the US (and cautious support of Britain), but the US link has cost her political capital, boosting Sharif.

Speculation rose in the past week after the arrival in London of Lieutenant-General Ashfaq Kiyani, chief of the ISI intelligence service, and other senior army colleagues, for talks with Bhutto. If, as part of a deal, Musharraf does agree to “take off his uniform” and step down as head of the army in order to retain the Presidency, then Kiyani, with deep support in the army itself, is one of two leading contenders to take over, and would automatically gain enormous influence.

The Sharif camp has been dismissive of the military delegation, calling them “emissaries of Musharraf”. Sharif denied that he would countenance any deal with “This man, Musharraf”, and claimed the support of the army “rank and file”.

So it is Sharif on one side, against an unstable potential alliance of Musharraf, Bhutto and senior army officers. The size of the crowds on Sharif’s arrival will be one guide to his likely success, hence yesterday’s staged pitch to the cameras. But if there is anything that could bounce Musharraf and Bhutto into their never-quite-consummated deal, it is yesterday’s show in the Dorchester.

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