Free trade agreements signed by Britain after its 2020 exit would effectively be voided if the country returns to the continental bloc, Labour officials under Keir Starmer warned. These officials told the government that membership would cost an additional £5 billion annually, primarily due to the loss of the Margaret Thatcher budget rebate. While the European Union may not require the adoption of the euro or the Schengen Area, EU counterparts indicated that accepting freedom of movement is a non-negotiable condition for entry.

The warnings follow Prime Minister Andy Burnham's announcement of a major review of European policy and a plan for a UK-EU summit later this year. Burnham, who stated that Brexit has "done more harm than good," is exploring options for a long-term relationship that range from a customs union to full re-entry. French President Emmanuel Macron and Spanish Prime Minister Pedro Sanchez welcomed the prospect, though Brussels officials remain wary of British policy volatility. UK carbon prices surged following the announcement.