The last time Manchester United searched for a manager, executives used a codename: Project MUM (Manchester United Manager). The process, undertaken over several months during Ralf Rangnick’s time as interim manager, led to the consideration of Tuchel and Mauricio Pochettino before ultimately ending at Ten Hag. A key factor persuading United was Ten Hag’s perceived over-performance relative to Ajax’s expenditure on wages and transfer fees.

The follow-up was christened Infinite MUM, in a nod to looking at prototype managers who would be lined up for years to come. The idea, led by Murtough and Dominic Jordan, the club’s director of data science, aimed to provide United with a modern system for selecting managers in the mould of Brighton and Liverpool.

Whether Ratcliffe paid much credence to Infinite MUM is unclear, but INEOS started with a particular profile to target: young head coaches playing attractive football who would work in a structure. An ability to create a culture at the club was also high on the agenda, which is why Gareth Southgate had support from some within INEOS given his work with England.

On this basis, they also opened dialogue with Kieran McKenna’s representatives. McKenna, who has guided Ipswich Town to back-to-back promotions, then met with United officials in the week before the FA Cup final. Ultimately, McKenna signed a lucrative new contract with Ipswich, with some uncertainty over United’s course of action in the immediate aftermath of Wembley.

Some people briefed on the situation felt Chelsea’s decision to part ways with Mauricio Pochettino on Tuesday, May 21 provoked United into accelerating their contingency planning, given the London club also explored the idea of making McKenna their new head coach before appointing Enzo Maresca.

The dominoes had been set off by De Zerbi’s departure from Brighton, with McKenna under consideration there, too. United officials felt they might miss out on a candidate or two if they waited until after the FA Cup final on May 25, a week after the end of the Premier League season.

Thomas Frank was another under consideration at Chelsea, for example. He met United on the Friday. In February, Frank had dined with Ratcliffe, as well as Frank Lampard and Roy Hodgson, after the launch of the Grenadier Fusilier, an INEOS car, in London.

It was a week in which club executives went on a series of interviews to assess the credentials of would-be Ten Hag replacements. As he and the players prepared for Wembley, the people in power hit the speed-dating circuit. The list of names reads like a who’s who of managers and includes some surprises.

De Zerbi was initially sounded out that week. Marco Silva met face-to-face on Thursday, around the time Ten Hag was speaking to the media insisting he was planning for next season. Pochettino, who Sir Alex Ferguson still champions, and Tuchel had meetings in London around the Wembley showpiece.

Jimmy Worrall, who founded the networking group Leaders in Sport with Brailsford, was a facilitator of the meetings. Worrall has a long-standing relationship with Southgate. Other names were discussed. There were talks over Ruben Amorim, who has won two titles with Sporting Lisbon, but he did not make the final reckoning. Roberto Martinez was also considered in the early stages.

INEOS weighed up two strands of thought: on the one hand, looking into progressive coaches outperforming expectations at smaller clubs; on the other, high-calibre established managers who would feel at ease in the Old Trafford dugout. Going for someone in the former category might prompt disappointment in fans but tap into a world-class talent on the way up; the latter would help to attract signings but also bring greater personal demands.

Several people involved held differing opinions over the best direction and keeping Ten Hag was always a consistent option, even if that appeared unlikely at times. On the eve of the FA Cup final, amid reports of Ten Hag’s demise whatever the result, Brailsford told several people that no final decision had been taken. Despite the flurry of activity, that vow was correct.

At that point, there was every expectation of Ten Hag’s departure, but the definitive call had not been made, with United wishing to first explore all options and take stock of events at Wembley as well as reflect on the season as a whole. Ratcliffe, Brailsford, Blanc and Wilcox wanted to step away from the emotion of Wembley to continue to make inquiries and come to an objective call on Ten Hag.

United’s season had been largely awful, falling out of their Champions League group in last place, suffering 14 Premier League defeats, and recording a goal difference of minus one.

But the manner of United’s 2-1 win over City shifted the fan sentiment around Ten Hag. There had been an even split among supporters on his retention, but beating Pep Guardiola’s team with a clear game plan sent his approval rating skywards, with 75 per cent backing Ten Hag in a poll conducted by The Athletic. Those numbers were replicated in other surveys.

Part of the wave of support came from the manner of United’s victory, built on a compact 4-2-4 featuring two false nines in Bruno Fernandes and Scott McTominay that Ten Hag had trialled in the wins over Newcastle and Brighton. Those results gained buy-in from players and Ten Hag also showed them statistical breakdowns of United’s win over City at Old Trafford in the Premier League last season, as well as the defeat at Wembley the previous May (when United had better data for expected goals), to encourage belief. He played two inspirational videos to the players to strike an emotional chord.

INEOS figures had always said they would ignore the noise to analyse performances clinically, but people in the directors’ box reported a few anxious expressions, rather than pure happiness, at United claiming another piece of silverware. Those watching on sensed the pressure on the call over Ten Hag had become bigger.

The sight of Ferguson singing along to jubilant United chants was compelling and he went into the dressing room after the game to give his congratulations.

Ten Hag fielded questions on his future from journalists, relaxed with his team and staff at the Marriott Hotel that night where he delivered a speech to the room, and then went on holiday without having heard from those in power.

That the season review did not include input from one of the most crucial witnesses gave some a sign of which way INEOS intended to go, though there was a counterargument that including Ten Hag would have been akin to a student marking his own homework.

Ratcliffe and Brailsford deliberated the options during a retreat to a boat off the coast of Finland in the week after Wembley and continued interviews with prospective candidates.

Pochettino fell out of the thinking during the first week of June, but Tuchel made a real impression. He is said by those familiar with the process to have come across incredibly well in person, eventually leading to United discussing possible financial terms during a meeting in Monaco two weeks after the FA Cup final. But no agreement was reached and Tuchel stepped out of the process. He is now expected to take a break from football.

United representatives then also spoke about salary expectations with De Zerbi, but the fit did not seem right. Ultimately, INEOS weighed up whether any of these candidates would be an improvement on Ten Hag and they came back round to their original intention before that board meeting in Monaco.

• The Athletic report