Officials from the previous Keir Starmer government warned that re-entry could cost an additional £5 billion per year due to the loss of the budget rebate secured by Margaret Thatcher. The EU has expressed openness to engagement but indicated that freedom of movement would remain a non-negotiable condition for any return. Additionally, rejoining the bloc or entering a customs union would invalidate various free trade agreements Britain has signed since Brexit, though UK carbon prices rose following Burnham's announcements.
