Rejoining EU customs union should be on the table, says London mayor, with UK-Brexit deal due for review

“I’m not saying today we should rejoin the European Union. What I’m saying is that (shadow foreign secretary) David Lammy is onto something when he’s saying we should have a closer relationship with the European Union.”

He said that “the economic cost of this extreme hard Brexit is huge” as he criticised the “omerta”, or pact of silence, meaning “you can’t talk about being close to the European Union, joining the single market, joining the customs union”.

Khan also said Prime Minister Rishi Sunak’s government is using its Rwanda deportation plan “in the same way they used Brexit – as a deflection of all the problems they’ve caused to our country”.

He called for the Labour Party to “speak up” on the benefits of immigration and diversity.

Shadow Northern Ireland secretary Hilary Benn touted the benefits of a stronger alliance with the bloc amid growing geopolitical uncertainty.

He said the EU will breathe an “audible sigh of relief” if Labour wins the general election later this year.

“The EU is a bit tired of negotiating with Britain,” he said in a speech at the think tank’s event.

“Now I am a great believer in the healing qualities of time.

“And there is no doubt that the arrival of a Labour government, if we win … will be greeted in the EU with a big and audible sigh of relief.

“And I think eventually there is going to be a moment when we look at each other across the Channel and say ‘you know what, we’re still big and important trading partners, we’re still friends and allies, we are cooperating on foreign policy and security and we need to do more of that … so wouldn’t it make sense to have a closer relationship?’”

‘Obvious it isn’t working’: London mayor says Brexit cost UK over US$178 billion

He said this is important for the economy and for “building alliances in a dangerous world”.

The Labour frontbencher pointed to conflicts in Ukraine, the Middle East and Sudan, tensions over Taiwan, the threat of climate change and the risk of a second Donald Trump presidency.

“We should come together with those who share our common values to defend those values in the face of these threats,” he concluded.

“The best way to protect your sovereignty is to work with others.”