For good or ill, David Frost knew how to get under Michel Barnier’s skin. The British chief negotiator’s habit in the negotiating room of dismissing the EU as “your organisation”, as if it was a bowling club, grated with his French counterpart. “You ask for respect for your sovereignty, David, but please respect ours,” Barnier privately chided Frost. Throughout many months of talks, theirs was never the warmest of relationships. “I don’t know if they will stay in touch,” admitted one EU source. But there was strategy at play: change conventional wisdom, the UK reasoned, and instil a genuine belief in Brussels that this administration could walk away. Frost, 55, had recognised the importance of changing the terms of the conversation in Brussels while working in the UK’s permanent representation in the Belgian capital in the 1990s, and as deputy head of the Foreign Office’s EU external department in London. On leaving the diplomatic service in 2013 to head the Scotch Whisky Association, he wrote a pamphlet on how to negotiate with the EU in the context of David Cameron’s renegotiation of Britain’s membership. “Make what you want seem normal,” he said then. And in 2020 Frost would tell his team: “People get used to ideas.” Frost – “Frosty” to his team or “the Great Frost” to the prime minister – did want a deal, albeit a thin one. He had extolled the economic value of access to the single market in the past. He had put his negotiating positions through “star chambers” of officials from Whitehall departments for interrogation, warning that ambitions should be kept within reason given Downing Street’s unwillingness to sign up to EU rules. As he saw it, this negotiation was not about limiting damage to trade by scaling down from EU membership. It was about building up access to the single market from the basis that Britain would make its own laws, unencumbered. The heart of the deal was known, given the UK’s red lines and the lack of time for elaborate negotiations: zero tariffs and zero quotas on goods. British officials believed a new narrative was key to making the EU engage with Downing Street’s scepticism about “level playing field” provisions limiting the government’s right to set its own regulatory standards. “They stressed sovereignty and taking back control constantly,” EU diplomats were privately briefed following the first round of talks in March. Or as a British official put it: “They found it very difficult to deal with our obstinacy. It was wearying. After another session of telling them we were a sovereign equal and an independent coastal state we would all say to ourselves ‘never again’. But David [Frost] would then get us to go in and do it again.” The British negotiators deployed the “Diet Coke manoeuvre”. “Diet Coke doesn’t make so many different flavours because of the taste,” said an official. “They do it so you are choosing between five different types of Diet Coke and a Pepsi. I would give them five different options that were more or less acceptable and get them to choose.” Uncertainty about Britain’s commitment to staying at the negotiating table was also drilled in from the start – and amplified by the definition of a no-deal outcome as equivalent to leaving on Australian terms. “It was a Trumpian use of alternative facts,” said one EU source. “The closer you got to the talks, the more you thought: this could end in no deal,” said another. “The closer you are to the action, the more you doubt.” Frost himself was an enigma to the EU side. A former Foreign Office man, steeped in EU affairs through postings in Brussels and Whitehall, but now a political figure sitting as a Conservative in the House of Lords, with Johnson promising him another massive role as national security adviser. A scholar of medieval French who had his team wear union jack branded lanyards: Frost may have been personally understated, but his negotiation had swagger. Following the UK’s dramatic mid-October walkout, Frost had been in no rush to resume the talks even when his demands had been fully met. Through gritted teeth, Barnier had reiterated his respect for UK sovereignty and the need for mutual compromise in a speech to the European parliament. But Frost let Brussels hang for a while. “The speech was in the morning but David was very calm and he said to hold off,” a UK source said. He wanted to see all the Is dotted and Ts crossed on new terms of reference for the intensified talks. It would take several hours before he picked up a phone in an office in No 9 Downing Street to restart the negotiations. “David’s super power is that he is so, so calm,” said a British official. As a consequence of this bullish approach, the negotiation was marked by public and private spats. By far the most explosive move came in September with publication of the internal market bill, rewriting the withdrawal agreement and breaking international law. “It focused minds on some of the problems in the negotiation,” said one UK source. For others, the breach of trust was cataclysmic. Lord Kerr of Kinlochard, for whom Frost worked as private secretary when he was head of the diplomatic service, said the losses were tangible, notably the block on a swath of UK-headquartered financial services from serving the European market – a unilateral EU decision. “That doesn’t feel like it’s played out well,” Kerr said. Time will tell. Frost has said the short-term costs of Brexit will be more than matched by long-term benefits, as the UK can plot its own way. Thanks in no small part to him, the country has the opportunity to find out.