On Monday night, Liz Truss was holding forth at a victory party on the rooftop of Deliveroo’s headquarters in Cannon Street, before leaving early to prepare for her audience with the Queen the next day. Thérèse Coffey, her soon-to-be deputy prime minister, hit the dance floor along with aides. Little did they know that their sense of jubilation was to be shortlived. With just hours of experience as prime minister behind her, Truss has found herself leading the nation through a period of mourning following the death of the Queen on Thursday afternoon. However, in the few short days before all government business was effectively suspended, Truss was not idle. She managed to complete a relatively hitch-free cabinet reshuffle, announce a £100bn-£150bn package of relief on energy bills and replace almost the entirety of Boris Johnson’s Downing Street operation. Truss had evidently prepared to a high degree as it became obvious she would triumph over her rival, Rishi Sunak. Over the last three weeks of the campaign, she spent much of her time planning for government with a clutch of close aides at her grace-and-favour retreat in Chevening. Johnson opted for a firing squad approach to his cabinet in his first days as PM, summoning them to his Commons office, dispensing with their services and letting shocked and sometimes tearful former ministers then head down to the Palace of Westminster courtyard where journalists captured their expressions. However, Truss had much of the logistics stitched up before she even entered No 10. She was also a diplomat; awkward conversations took place by phone over the course of the last week so that those who were departing would be prepared. Negotiations over positions for ambitious leadership rivals took place over days, sometimes weeks beforehand, ensuring there would be no standoffs in No 10 to set tongues wagging. Two of the square pegs who Truss found most difficult to fit in were her leadership rivals Kemi Badenoch and Penny Mordaunt. Badenoch had been keen to take over as culture secretary and Mordaunt rejected the job of party chair. Friends of Mordaunt, who came a close third to Truss and was subject to a damaging campaign against her mounted by Truss supporters, said she had been hoping to be foreign secretary. But Truss opted to place her most ambitious potential challengers in low-key jobs with little chance to build substantial policy profile. “If you’re Liz you don’t want Kemi in the Telegraph every week with juicy ideas,” one MP backing Truss observed. “She is quite obviously more of a future prospect for the party than Penny or Suella [Braverman, the home secretary] now.” The reshuffle publicly started on Tuesday but appointments went on late into the night largely because of calls between Truss and foreign leaders, the most important with the US president, Joe Biden, and Ukraine’s president, Volodymyr Zelenskiy. Biden took the moment to underline the US’s warnings over the Northern Ireland protocol. A White House readout referred to the countries’ “shared commitment to protecting the gains of the Belfast/Good Friday agreement and the importance of reaching a negotiated agreement with the European Union on the Northern Ireland protocol”. The UK readout skirted over the same detail. Truss finished around midnight, but aides said she was back at her desk by 6am, preparing for cabinet. As for her rivals, most of Sunak’s most prominent backers were on the the Commons terrace after losing the leadership contest on Monday. Departing ministers, including Grant Shapps, George Eustice and Steve Barclay, bought rounds of farewell drinks for their staff before they had even been told officially that they were out. Shapps had been one of the few Sunak-backing ministers to put up a fight to try and keep his department, having spent the summer making a series of announcements on strikes. But he was ousted along with all the others; the one survivor was Robert Buckland as Welsh secretary. He had tactically switched sides during the contest. Buckland had hoped for a return to the justice department, where he had served before being ditched by Johnson, but he was mollified with a pledge to overhaul the bill of rights, which he had grave concerns about. In contrast to the glum Sunak gang, there was a big smile on the face of Keir Starmer as he strode on to the terrace late on Monday afternoon for a rare appearance with his aides and a gang of MPs leaving a meeting. On arrival, Starmer was mobbed by Conservative MPs, two of whom jokingly congratulated him on winning the next election. Two former ministers said they were despondent about the party’s future, with one saying throwing themselves in the Thames was a similarly appealing prospect. One current serving minister said they were concerned that a mass clearout of Sunak supporters would entrench divisions in the party. They said there was widespread concern that Truss would conduct her government in a similar style to Johnson, forced to make U-turns and with a “bunker mentality” alienating critics. “If I was Liz I would be careful about those who got onboard with her because she is continuity Boris, because the diet version will never be the same as the real thing to them,” the minister said, in a covert reference to her appointment of Jacob Rees-Mogg, a close ally of Truss’s predecessor. One former minister said they felt new freedom to speak their mind with Truss’s election. They said: “Ultimately I was very loyal to the government, I think, and now there are things I want to say that I don’t agree with and there’s a lot of people feeling like that now.” Another said a more widespread unease at Truss’s election had been compounded by the lower than expected margin with which she beat Sunak, pointing out fewer than 30 MPs had backed her publicly in the first round of voting. “In my lifetime I have never seen a PM coming in with lower political capital.” But those who were in for the biggest shock were not the felled Sunak supporters in the cabinet, but the Johnson-era staff in Downing Street, many of whom expected to stay on under Truss – or at least had asked to do so. Political advisers received an email as Johnson departed Downing Street telling them to clear their desks by 9.30am. Truss’s team also made it clear she would be dismantling Johnson’s reforms of the No 10 operation, and at least 40 civil servants were told directly about their new roles in the Cabinet Office. Even David Canzini, a former colleague of Truss’s new chief of staff, Mark Fullbrook, and a firm Brexiter, was not asked to stay on. Truss will now have to contend with a break in her plans for government, using the time to take stock and work out the details of her energy bailout – which was published without an explanation for how it would be funded. When business returns after 10 days of national mourning culminating in the Queen’s funeral, Truss will have a huge amount to get done in a compressed period of time, from a visit to the UN general assembly and an emergency budget, to a slew of policy announcements that will be expected at her first party conference. Politics may not be as pugilistic as normal this autumn, but the new prime minister’s intray is still building up, with her government bracing for an economic crisis, potential energy shortages and an NHS on its knees before too long.