Andy Burnham has been warned that the UK gaining full entry into a major global trade pact will not come close to covering for losses from leaving the EU despite a £2bn boost to the economy.

Full membership in the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP) took effect on Tuesday, 1 September, after Canada ratified the country's accession in July.

Britain initially signed up to the deal under Rishi Sunak’s government in 2023, with implementation commencing the next year as participating nations formally approved the expansion. Canada served as the final member among the 11-nation trading bloc to sanction the UK's participation.

But the good news is overshadowed by revelations, carried last week by over the way the UK has lost £11.7bn a year on exports as a result of Brexit.

Campaigners have warned that it means that the CPTPP boost - which hard Brexiteers had promised would make up for losses from EU trade - will not come close to closing the trade gap caused by leaving the EU and its Single Market.

Mike Galsworthy, chair of the European Movement UK, said: “While £2 bn a year isn't to be sniffed at, even if it only reaches that figure after about 15 years, what it doesn't do is plug the Brexit black hole. The OBR still scores leaving the single market at 4 per cent GDP, roughly £120 bn a year. That's sixty times bigger.

“And let's be honest about what we've joined. We already had trade deals with nine of the eleven members, most of them inherited from agreements the EU negotiated.

“Meanwhile the EU has signed Mercosur, and struck a deal with India that was more generous than our own. So yes, it's nice that our business people can stay longer in Canada. But look at the glaring geopolitical weather: Canada and the EU are coming together fast, without us.

“This year Canada became the first non-European country admitted to the EU's €150 billion defence procurement programme, which we are still not in, and [Mark] Carney is coming to the EU's State of the Union address. Britain should be the country convening the EU and CANZUK from inside both, an architect of the future geopolitical shape. Instead we're bragging about crumbs from side deals on the sidelines.”

Liberal Democrat trade spokesperson Joshua Reynolds said: “This deal is simply no replacement for trade with our closest and largest partners in Europe.

"If the Government are serious about real economic growth, they must stop pretending far-flung trade agreements will fix the problem and focus on re-joining the customs union, and crucially re-entering the Single Market.”

The row comes amid concerns that Mr Burnham has said he will stick to Keir Starmer’s controversial red lines of not rejoining the EU, Single Market or Customs Union or looking at free movement again despite the harm being done by Brexit to the UK economy.

Naomi Smith, chief executive of Best for Britain, which campaigns for the UK to restore its EU membership, said: “Independent modelling by Frontier Economics found there’s at least £92bn on offer from UK membership of the EU which makes the value to Britain’s coffers from the CPTPP deal look like a rounding error.

“Burnham should take a leaf out of Carney’s book: while Canada has decided closeness to the EU is a strategic asset, the UK is busy pretending other deals will make up the losses.”

Under the terms of the arrangement, UK companies with operations in Canada will experience facilitated travel to the North American nation. Qualifying corporate visitors are now permitted stays extending up to six months, replacing the former restriction of 90 days within any given six-month timeframe.

Taken together, the combined economies of all CPTPP signatories stand at nearly £10 trillion as of 2025. Official Government estimates suggest the agreement will deliver an annual boost of around £2 billion to the UK economy.

Trade minister Lord Anas Sarwar said: “With full access to the CPTPP, there are now new opportunities for British businesses across some of the world’s fastest-growing markets.

“Whether it’s selling our world-class food and drink or winning public contracts, we will continue to back British business to succeed across the world, driving growth and creating jobs across the country.”

Membership of the trade group – established in 2018 and including Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore and Vietnam – is expected to bolster that investment relationship.

While Britain already has trade agreements with all CPTPP members apart from Malaysia and Brunei, officials said membership will deepen existing arrangements, with 99 per cent of current UK goods exported to the bloc eligible for zero tariffs.

Dairy producers will gain export opportunities to Canada, Chile, Japan and Mexico, while beef, pork and poultry producers will get better access to Mexico’s market, according to officials.

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