Warm wine, small talk and curling canapés have long defined the Westminster summer scene. But regime change has added a certain frisson to the party circuit this year. As many of Labour’s finest toasted America’s semiquincentennial at the US ambassador’s house last week, the hostility radiating from Keir Starmer’s No. 10 team was unmistakable.

‘I’ve had them shooting daggers at me all night,’ complained one rebel MP, amid toasts to the revolution. ‘It’s over guys, you lost.’ As fireworks exploded overhead, another added: ‘The king is dead, long live the king.’

The Prime Minister’s decision to step down, paving the way for Andy Burnham’s coronation, has spared his party plenty of pyrotechnics. Yet even the most stoic Starmtroopers struggle to conceal their contempt at the great rush to the Burnham cause. Labour’s church-like qualities have often been remarked upon. The party’s history books and the memoirs of its former leaders are peppered with talk of values, crusades and the faithful. But there is a slight whiff of the televangelist to some of the rhapsodising by newly converted Burnhamites. ‘Half of these people were begging us for jobs just a moment ago,’ grumbles one government aide.

Plenty of ambitious MPs are making what one Burnhamite calls ‘pilgrimages’ to see his key allies, pledging fealty, seeking truth and atoning for past sins. His two disciples are Louise Haigh, the former transport secretary, and James Purnell, his chief of staff. The former is advising on ministerial gigs, the latter on backroom staff.

Amid tearoom gossip about which MPs are exaggerating their northern accents, older hands ask if the current kumbaya spirit will dissipate in a fortnight’s time when the new cabinet is announced. ‘They’re quickly learning that 403 does not go into 21,’ says one veteran, referring to the number of Labour MPs and cabinet posts available.

Burnham dislikes this jockeying, but his lack of firm preferences incentivises such behaviour. ‘Everyone thinks it’s in their interest to essentially be in Andy’s face all the time,’ says an aide. With the great Labour beauty pageant now in full swing, a range of different approaches are being tried by ministers keen to cling on to their red boxes.

Plenty of ambitious MPs are making what one Burnhamite calls ‘pilgrimages’ to see his allies

The first are the briefers: those uncertain of their status, keen to press their claims. Those closest to Rachel Reeves have made foreboding noises about the bond market’s reaction if she was removed as Chancellor. Allies of Emma Reynolds, the Environment Secretary, have taken to punting around op-eds which make her case. ‘One can only hope that her outward support for Sir Keir will not be held against her,’ says one. Friends of James Murray, the Health Secretary, speak admiringly of ‘his professional, calm, firm’ approach to the resident doctors’ strikes. Even Lord Hermer has his admirers in the Tribune group of soft-left MPs.

Next, there are the up-and-comers: those confident of preference under the new regime. Some are members of the ‘Manc Mafia’, such as Lisa Nandy, who is tipped for the local government brief, and Jonathan Reynolds, who has endured a challenging spell in the whips’ office. Deputy leader Lucy Powell reportedly has her eye on Bridget Phillipson’s brief in education. Should Burnham find that there are too few posts to go around, then running the party – and picking a new general secretary – could serve as a substitute gig. Angela Rayner is said to be ‘relaxed’ about her fate, though her chief of staff, Nick Parrott, is currently offering informal advice to the Burnham camp.

Next there are the party men, the reserved middle-hitters of the cabinet, who watch with a degree of resignation. The likes of David Lammy can talk fondly of old ties with Burnham; Alan Campbell, the wily Leader of the House, might well take Reynolds’s job as chief whip. Some, such as Nick Thomas-Symonds, the Europe negotiator, could be useful to the Burnham project, if his recent brush with the ethics watchdog is not held against him. Finally, there are a small handful who seem to have accepted their fate, such as Peter Kyle, Steve Reed and Baroness Chapman.

Of all the cabinet appointments, none will be more important than who runs the Treasury. Within the City, there is a determined ‘stop Ed Miliband’ lobbying campaign under way. ‘The message being sent to Burnham is that if he picks Miliband, the government will be immediately in crisis mode with a chancellor who is seen as actively hostile to business and economic reality,’ remarks a plugged-in figure. A copy of ‘Go Big’ – Miliband’s 2021 manifesto – recently arrived on a leading hedge fund manager’s desk. Key economic advisers Andy Haldane and Jim O’Neill are both being lobbied, amid near-universal opposition from the banking sector.

Ideology is one factor determining Burnham’s decisions; identity is another. If Burnham does indeed make half his cabinet female, then it will be a ‘bad day to be a bloke’, says one pale, stale, male Labour aide. Just as his route to power was aided by northern and female MPs angry at Starmer’s ‘boys’ club’, Burnham will have to take care not to reawaken old fears of Labour’s ‘southern discomfort’ by jettisoning too many MPs in other parts of England.

Many of the junior aides within government are expected to be asked to stay on, just like the last Labour handover in No. 10 in 2007. Team Burnham has remained largely tight-lipped on personnel plans – though eyebrows have been raised at briefings around the role of Hayden Munro, billed as ‘Jacinda Ardern’s election-winning campaign director’. One New Zealand Labour source says: ‘If he’s after a job in Downing Street, let’s hope they don’t get references.’

Burnham’s coronation has limited any public criticism of his plans. For all the talk of Labour’s different traditions, there is no rival band waiting to take over if he fails, as the Sunakites did with the Trussites in 2022. He has promised a politics of devolution, community and civic renewal. Now comes the harder task: proving his ambition was justified. In a party that owes more to Methodism than to Marx, Labour is wagering that Manchesterism is more than the musings of one man.