It emboldened Starmer and his lieutenants. Rachel Reeves, the U.K.’s chief finance minister, used her speech at the Labour Party conference in Liverpool to talk up the benefits of improved cross-border mobility for the economy.  

Ahead of last week’s difficult budget stuffed with tax rises, she waded in further, damning the effects of a “chaotic Brexit.”

While the new rhetoric has yet to be backed up by a shift in policy, there are signs that some of Starmer’s close allies are starting to think bigger. 

Rejoining the EU customs union was reportedly raised as an option by Starmer’s economic advisor ahead of the budget — but was rejected. “There are definitely people who have been pushing at this for a long time,” one person with knowledge of conversations in government said. 

“I don’t think that will be that surprising to people, because if your primary goal allegedly is growth then that’s one of the easiest levers you can pull. Most economists would agree — it’s the politics that’s stopping it.” 

Pressed on the prospect of Britain’s applying to rejoin the customs union on Wednesday, Health Secretary Wes Streeting did not explicitly rule out the idea but stressed the government’s policy was about “new partnerships and new relationships, not relitigating the past.”

If Starmer opts for a risky manifesto-busting push to rejoin the customs union, diplomats say even that is unlikely to be a quick fix for the British PM. 

“It would take time. Just consider how slow has been so far the progress on SPS, ETS and Erasmus,” the first diplomat quoted above said. “As of now, the U.K. needs the EU to spur its growth, not the other way around.”