Labour has broken its long silence on Brexit, laying out detailed plans to improve, not scrap, the deal Boris Johnson struck with the EU, in a move it concedes will enrage remain supporters. On the sixth anniversary of the Brexit referendum, the shadow foreign secretary, David Lammy, confirmed the party would seek only limited changes and would not seek to rejoin the single market which would bring the return of free trade and free movement of people. “We are not going into the next election saying that we will enter the single market or the EU. “You might not like it but Labour is determined to govern the entire country,” he said adding “there cannot be a rehash of arguments” made in remainer constituencies like his in London. “The British people have made a decision and we have to honour it,” he told the UK in a Changing Europe’s annual conference. His remarks came just hours after former Brexit negotiator Lord Frost declared “Brexit is working” and said those who said it was damaging the economy had an “axe to grind”. Lammy pledged the party would seek to sign an agrifood agreement; to restore visa-free business travel for touring musicians and performers, and seek to improve haulage arrangements. It would also seek to restore mutual recognition for professional qualifications such as accountants and architects, seal a deal on financial equivalence for the City of London and secure associate membership of the EU’s £80bn Horizon Europe science funding network, something the EU is delaying because of the row over the Northern Ireland protocol. Without rejoining the single market or customs union, Labour’s approach amounts to a renegotiation of the trade deal which will come under regular review by both sides. In an impassioned speech, Lammy minimised the importance of not seeking a return to the single market but said he had the “scars” on his back” from past attempts to get a second referendum. “We’re not going over it again. And I’m afraid, psychologically, we’ve got to come to terms with that,” he said. Instead he reserved his opprobrium for the Conservative party’s attempts to unilaterally unpick the Brexit treaty with draft legislation to override some of the Northern Ireland protocol. “Boris Johnson’s Conservatives are stuck in a fever dream of 2016, picking petty fights with our closest allies instead of moving on and negotiating solutions,” he said. The “consensus among the economists” was that the deal Lord Frost had negotiated had “contributed to the UK lagging behind the rest of the G7 in trade recovery”. The UK would also have the lowest recovery among the G20 nations apart from Russia, he said. Lammy was speaking just hours after Frost had told the same conference that forecasts by the Office of Budget Responsibility were based on “zombie figures” based on academic studies which looked at the effect of opening up badly run ex-communist and ex-authoritarian autarchic economies”. As EU leaders met to support Ukraine and Moldova with a plan to give them candidate membership status, Frost asked how long Brussels would continue to “hassle and lecture” Britain and said the Conservatives had an option to take unilateral action to sort out Brexit in Northern Ireland. But Lammy said the EU was “aching” to restore relations and the government’s plans for laws to unpick the Brexit treaty was “reckless” and hypocritical for a country calling on dictatorships around the world to follow the law. “This protocol bill is a charter for lawlessness that serves the interest of those who want to weaken the rule of law,” he said. “One of the most troubling aspects of all of this is the dangerous legal distortion that’s used to justify it.”