Found the quote:
"In a recent speech justifying unilateral repudiation, Lord Frost, Johnson’s negotiator, argued that “The detail of the protocol’s provisions was essentially imposed under duress because we had no ‘walk away’ option.” As a matter of fact, we did. But it would have been too costly to exercise. In these negotiations the EU was (and is) in a stronger position, because it matters far more to the UK than them. This is power, which matters in international relations. Who knew? Not Frost, it seems."