Taoiseach Micheál Martin acknowledged the significant role played by Keir Starmer “in resetting the Irish-British relationship as well as relations between the UK and the European Union” in a statement reacting to the British prime minister’s resignation on Monday. “Since Keir took office two years ago, he has worked with us to set a new direction and depth in the relationship between Ireland and the UK, for the benefit of all our citizens, north-south and east-west,” the Taoiseach said. “Our two governments also took an important step forward in dealing with the legacy of the past in Northern Ireland, publishing a joint framework on addressing the legacy of the Troubles.”He described Starmer as “a person of great ability, decency and honour”. Martin defended Starmer earlier this year during an Oval Office meeting with US president Donald Trump, after Trump criticised the British prime minister.Martin said he had “no doubt that his successor as prime minister will wish to continue to deepen and strengthen the relationship between the UK and Ireland, and we will continue to work in furtherance of that objective”.Sinn Féin leader Mary Lou McDonald said the departure of Starmer provided an opportunity “to advance relationships between Britain and Ireland in a positive direction”.She said his successor needed to work with the Irish Government on the issue of constitutional change.“Sinn Féin stands ready to work constructively with the incoming British prime minister. We will continue to press for the planning and preparation needed for constitutional change. The constitutional status quo is no longer sustainable. Partition has failed. Both the British prime minister and the Taoiseach have a responsibility to engage with these realities in a responsible, practical and direct way that shapes the future,” she said.In Dublin, officials anticipate a continuation of the vastly-improved relationship between the Irish and British governments under the Starmer administration. The relationship had deteriorated badly in the wake of Brexit and through the long and tortuous years of the Brexit negotiations, as the UK, the EU and Ireland haggled over the terms of the UK’s exit and the arrangements for future relations. Many elements within the then ruling Conservative Party blamed Ireland’s stubbornness for the UK’s failure to negotiate a smooth and advantageous exit from the EU, and this bled into wider political relations between London and Dublin.The last Conservative prime minister, Rishi Sunak, was viewed as having made a substantial effort to improve the atmosphere. But the arrival of Starmer in 10 Downing St heralded a step change, after meetings in Farmleigh and in Chequers, the friendlier relations between the taoiseach and prime minister – as shared by Bertie Ahern and Tony Blair, and later by Enda Kenny and David Cameron – were restored. [ ‘I can’t overstate the significance of this meeting’: Harris and Starmer begin Anglo-Irish ‘reset’ at ChequersOpens in new window ]Relations throughout the two governing systems improved. Starmer had an instinctive empathy with Ireland – famously he wore a Donegal jersey playing five-aside football – and a knowledge of Northern Ireland from previous government posts. Dublin may be sorry to see him go, but officials are confident that his likely successor, Andy Burnham, will be just as friendly. He has spoken of his Irish heritage, which he traces back to Drogheda in the late 1800s. He is a Catholic and served as an altar boy in the heavily-Irish influenced world of Liverpool Catholicism. He has spoken about how that Catholicism – communitarian, compassionate, politically left-wing – influenced his politics. He used to say how three institutions had shaped his life – Everton Football Club, the Labour Party and the Catholic Church. This is not someone that Irish politicians will find incomprehensible. As mayor of Manchester, Burnham was a relatively frequent visitor to Ireland. “I know Andy, I’ve met him on a number of occasions, he’s taken a particular interest in Ireland and he has come to see us on a number of occasions,” Martin told reporters in Brussels on Friday morning as news of Burnham’s victory in the Makerfield byelection broke.During the campaign, Burnham told The Irish Times that he would seek to “carry that relationship [between Ireland and the UK] forward”.Dublin will watch two fronts especially closely. The first is how Burnham pursues closer relations with the EU – something with which Irish help could be significant. The second is his broader political success – can he take on and beat Reform, as the byelection suggested, and scupper the chances of Nigel Farage becoming prime minister? Ten years and six prime ministers on from Brexit, the UK’s politics continues to oscillate wildly. Ireland watches more anxiously than most.