How should the EU interpret the trade agreement between the US and the UK?

"I think it [a US trade deal with the UK],will cause a certain amount of irritation in Brussels. And it's not because there's a direct conflict between the EU and the UK. It won't jeopardise the relationship between the EU and the UK. But it does set a bad precedent," says Aslak Berg, a researcher at the Centre for European Reform.

"By authorising the maintenance of these customs duties, it reinforces the legitimacy of these customs duties, which are contrary to international law," he continued, adding that the decision "will not cause permanent damage to relations between the European Union and the United Kingdom."

Berg points out that the case of London is unique.

"The UK is in a different position to the EU in some respects. The UK doesn't have a trade surplus with the US and that's a big priority for the Trump administration."

The researcher also glosses over more subjective factors. "Trump likes the UK. He likes being invited to Buckingham Palace. He liked the state visit. And he, Starmer, found a way to talk to Trump which enabled him to get on very well on a personal level. And that counts for a lot," said Berg.