When Boris Johnson flew to meet Donald Trump for the first time at the Biarritz G7 summit in 2019, he boasted en route to reporters about the huge benefits a post-Brexit trade deal with the US would bring – citing a baffling range of great British products, from pork pies to shower trays.

Despite the positive chemistry between the two blond blowhards, and the launch of formal talks the following year, no agreement was ever reached.

What the US and UK now appear to be aiming at, after Keir Starmer’s trip to Washington, is not a broad-based free trade agreement like that contemplated (unrealistically) by Johnson, and covering a range of sectors – but something much more limited.

The suggestion from No 10 has been that the two sides will draw up a narrower, economic deal, focusing on cooperation in technology.

That is for good reason: even before Trump appeared on the scene, there was little enthusiasm in the US for deepening trade cooperation with other countries.

The last new US free trade agreement that came into force was with Colombia, in 2011 – aside from the USMCA, a reworking of the Nafta deal with Canada and Mexico, which Trump signed in 2020 and is now busy smashing up.

When it comes to the UK specifically, any broad-based deal would be likely to bring into play two issues that are highly problematic politically.

These are: agriculture, where the US has different approaches that the UK is unlikely to want to accept – such as washing chickens in chlorine; and the NHS, widely viewed as a huge prize for the US life sciences sector.

Washington’s published negotiating aims for the last attempt at a post-Brexit trade deal, in 2019, included achieving “comprehensive market access for US agricultural goods in the UK”.

Labour’s stated aim of striking up a closer post-Brexit trade relationship with the EU creates an added barrier to this kind of deal, because accepting US food standards, for example, would scupper any veterinary agreement with Brussels.

The health secretary, Wes Streeting, said the NHS would not be “on the table” in any potential negotiations; though he did point to the value of sharing data, in exchange for UK patients benefiting from new treatments – an argument that may alarm privacy campaigners.

“We’re not in the business of selling off people’s data, but in terms of data access, absolutely the thing that the NHS can offer and the thing that the NHS can get in return is being a really strong partner for clinical trials,” he told the BBC.

John Springford, of the Centre for European Reform, suggested a narrow, tech-focused deal could include the UK promising to adopt a similar approach to artificial intelligence regulation, for example – where the US has strongly criticised the EU’s more stringent legislation. “That could be preferable to getting into the weeds of a free trade agreement,” he said.

The UK’s refusal, alongside the US, to sign up to a declaration on “inclusive and sustainable” AI at the recent Paris summit may have been an early signal of the two countries thinking along similar lines.

Given the UK’s determination to increase defence spending rapidly, there could also be some promise of collaboration on arms procurement (although Trump did momentarily fail to recognise Aukus, the acronym for the Australia-UK-US security alliance).

Ultimately, the main aim of any deal will not be to carve out new markets for UK exporters, whether of pork pies, shower trays or anything else – but to dodge the tariffs this second Trump administration is using to reshape the global trading system.

That is a very different proposition to the broad-based agreement Brexit’s most fervent fans once contemplated, drawing the UK closer to the US economy and away from the EU. But given what Trump is preparing to visit on many other countries, it could be a big win.