Labour governments were once famed for doing deals over beer and sandwiches in Downing Street. But under Keir Starmer, a charm offensive to win the backing of the world’s most powerful bosses required a bit more.

After a rain-soaked day of meetings and speeches at the 15th-century Guildhall in the heart of the City of London, the hundreds of bosses from global firms including Goldman Sachs, BlackRock and HSBC were whisked by private coach, escorted by ceremonial military guard, to St Paul’s Cathedral.

The order of the evening: an exclusive reception with King Charles, entertainment from Elton John, and dining by the three-star Michelin chef Clare Smyth, as Labour pulled out all the stops to woo the captains of industry – helping to secure what it tallied as £63bn of foreign investment pledges.

It came after a glitzy bash at Lancaster House on Sunday night – in the more informal surrounds of a mansion on the Mall, a stone’s throw from Buckingham Palace, where guests were treated to canapés, Chapel Down wine and BrewDog beer.

But there were tough issues to solve, too – including the fallout from an explosive cabinet row involving Louise Haigh, the transport secretary, after the Dubai-based company DP World threatened to withhold an announcement of £1bn of investment in Britain.

Over a breakfast of kedgeree at the Guildhall, the prime minister and his business secretary, Jonathan Reynolds, sought to smooth over the problem. There were though no apologies, and Haigh was not present. Yet she was, along with the rest of the cabinet, at the investment summit throughout the day.

Beyond a big bash to show Britain was “open for business” again after the chaotic years of Conservative government, the prime minister inviting the money changers to the temple had a symbolic message. Labour wanted to roll out the red carpet for private investment. It was the key to the government’s national mission, Starmer told the ranks of bosses in the Guildhall’s stain-glassed 19th-century Old Library.

“You are pivotal to this great cause of our times,” he said, in a speech opening the event, near the Guildhall school of music, where the prime minister played flute as a student.

After grumblings about whether the summit could be a flop – given its awkward timing two weeks before the chancellor Rachel Reeves’s budget – the guest list was in the end a who’s who of global business.

The CEOs of Goldman Sachs and BlackRock, David Solomon and Larry Fink, were there, alongside the chiefs of Lloyds Banking Group, HSBC, Barclays, and Brookfield. So packed was the Old Library that Andrew Bailey, the governor of the Bank of England, was sat a handful of rows from the back.

Some Labour ministers were clearly enamoured of the attention. “Are you enjoying Davos in London?” Reynolds asked journalists from the world’s media – who were forced to stay in the Guildhall crypt, an area dating back to the time of Edward the Confessor.

“Personally I’m enjoying it a great deal,” the business secretary said. “I think you can feel the buzz in the room. It is incredibly exciting.”

Among bosses the mood was more one of curiosity. “We’re here to listen,” said the head of one global bank. Several of the most powerful CEOs had time for intimate chats with members of Starmer’s cabinet. Executives from Airbus, Rolls-Royce and Google also had a chance to question the new head of Labour’s industrial strategy council, the Microsoft UK CEO Clare Barclay, on the party’s flagship policy, on the day it was launched.

Andrea Rossi, the chief executive of M&G investments – among one of the headline sponsors who were quoted up to £250,000 for involvement – said it was a “positive day” showing the UK had returned to stability after turbulent years caused in part by Brexit and Covid.

“There is to a certain extent a renaissance of the UK, as people are looking at the UK again,” he said.

The new government wanted to be pro-business, Starmer said. pledging that his door was always open to companies who could help to shape policy. However, Labour’s socialists roots were not entirely for sale.

Starmer insisted any bulldozing through regulation would still protect important issues, highlighting the importance of fire safety rules after the Grenfell Tower tragedy. Labour’s workers’ rights changes were also vital for growth.

Eric Schmidt, the former chief executive of Google, on a panel with the prime minister, had some tougher words. While nodding his head, he urged the Labour cabinet to “move on this agenda [of growth], as opposed to just going like this”.

“I was shocked when Labour became strongly in favour of growth,” he told the audience, picking up the feeling many investors have had about the party’s stance on the economy in recent years.

“Wealth creation is the number one mission of a Labour government,” said Starmer. “It’s true!”