Sir Keir Starmer has claimed the big winners from Donald Trump's state visit were the British public, who he argued had reaped the economic benefits flowing from the pageantry and praise ladled on the president.

Starmer, whose courting of Trump is widely seen as one of the few big successes of his premiership, has succeeded in taming Trump's tariffs on Britain, notably on cars, aerospace and -- with slightly less effect -- steel.

The £150bn of investment by US companies in Britain hailed by Starmer as being linked to the state visit was a familiar Downing Street tactic -- adding up a series of planned commercial decisions to come up with a big number, then claiming some of the credit.

Nevertheless, allies said Starmer was "really delighted" at the commercial buzz around the visit. He badly needs to persuade voters that he has a compelling growth strategy ahead of the November Budget.

Some in Britain, like Liberal Democrat leader Sir Ed Davey, find the flattery of Trump distasteful. Davey boycotted the state banquet at Windsor Castle over Trump's stance on Gaza.

As Trump returned to Washington on Air Force One on Thursday evening, what did the commercial deals actually amount to?

Technology

Multibillion-pound investment pledges by Big Tech companies including Microsoft and Nvidia were a focus of this week's US-UK agreements.

UK tech investors and entrepreneurs broadly welcomed the plans to build several new computing facilities dedicated to artificial intelligence. Nvidia chief Jensen Huang had earlier this year highlighted the UK's "surprising" lack of AI infrastructure.

Microsoft said it would spend $30bn (£22bn) in the UK over the four years to 2028, of which half would go towards building AI infrastructure, including the UK's largest new supercomputer.

Nvidia said it would invest £500mn in UK cloud computing start-up Nscale as part of a deployment of 120,000 of its chips in the UK, giving the country the largest cluster of AI computing power in Europe. Huang also pledged to do more to support the UK's AI start-up ecosystem, which he said had been "supercharged".

The opening up of the UK to Silicon Valley's technology and investment will be a win for the US as it vies with China in the battle for global AI sovereignty.

The memorandum of understanding between the two countries points to the UK's "advancing pro-innovation AI policy frameworks". Some have interpreted that as an agreement by Britain to implement lighter-touch tech regulation.

Tony Wang, tech portfolio manager at T Rowe Price, said the UK offered "scale with less bureaucracy" than the rest of Europe.

"The UK is increasingly positioning itself as a bridge between US tech capital and European demand," he said. "London is closer in mindset to Washington than Brussels, and that matters as companies commit long-term capital."

Nuclear

The Trump administration has fiercely criticised the UK's plans to stop new domestic oil and gas exploration. But on nuclear energy, the two countries are more aligned.

This week, the US and the UK signed a deal to speed up nuclear reactor design checks by lessening duplication between their two regulators, fulfilling a long-held wish among developers of new advanced or modular designs. Meanwhile, UK and US companies including Centrica, X-energy, Holtec, and Last Energy announced tie-ups to develop small modular or microreactors in the UK. UK engineering giant Rolls-Royce said it had entered its small modular reactors into the US regulatory process.

The planned projects in the UK could provide an important boost to Britain's power supplies in the 2030s, helping to meet growing demand from electric cars and data centres. But both the technology and the plans are at a very early stage and still need to raise billions of pounds and pass several regulatory steps if they are to become a reality.

Reactor designs are still being developed, while the various tie-ups are mostly at the stage of memorandums of understanding or joint development agreements.

Tone Langengen, senior policy adviser for climate and energy policy at the Tony Blair Institute, said the agreement was a "statement of confidence and intent" more than anything.

But she added: "It is now up to the UK government to focus on delivering this. There are definitely viable pathways where the next steps can be worked out and those deals can become real, deliverable projects."

Steel

Hopes that Trump's visit would cement a deal announced in July to reduce tariffs on steel exports to the US to zero were blown even before the president landed on British soil. The government said before his arrival it had conceded a permanent 25 per cent levy that would provide "stability" for the industry.

Although the 25 per cent levy is less than the 50 per cent tariff slapped on other countries' exports, it will increase pressure on an industry that is already struggling with high energy prices and a glut of Chinese steel.

Sam Lowe, trade lead at consultancy Flint Global, said there was a lesson from the episode: "Even if you're in Trump's good books it doesn't mean you get everything you want."

A 25 per cent tariff on steel was better than 50 per cent, he said.

But he added: "It's certainly not everything the industry wants."

The 25 per cent tariff hits not just UK steel manufacturers but also other companies that use steel in products that they export to the US -- such as the Staffordshire-based digger manufacturer JCB. The US is the UK's second most important export market, totalling 9 per cent by value of exports.

Gareth Stace, director-general of trade body UK Steel, said: "The reality is that the deluge of heavily subsidised steel flooding into international markets is forcing countries across the world to erect trade barriers to protect their industries."

Blackstone

Private equity giant Blackstone made by far the biggest headline commitment to invest in the UK, expecting to invest £100bn over the next 10 years across private equity, real estate and credit.

But, crucially, the group did not say it would invest £100bn of equity. The figure includes the debt that the firm will use to buy assets, and Blackstone's own lending to other companies and infrastructure projects.

Because Blackstone has not disclosed how much it has deployed in the UK over the past 10 years, a direct comparison of past and announced deployment rates is impossible. However, the firm currently holds UK assets worth $107bn, or roughly £79bn, including debt, such as digital infrastructure and ecommerce warehouses.

The £100bn pledge is part of a previously announced plan by the US company to deploy at least $500bn across Europe over the same period.

A top executive at a British private markets firm said: "A bunch of these things were probably going to happen anyway."

Rachel Reeves, UK chancellor, has assiduously courted Blackstone chief executive Stephen Schwarzman since Labour's election victory, holding a private dinner with him in New York last August.

Blackstone also has large corporate investments in the UK, including Merlin Entertainments, the owner of Legoland. It was a significant shareholder in the London Stock Exchange's parent company until fully divesting its shares last year.

Starmer 'really delighted' with Trump visit investment deals -- but details critical