London – Theresa May was heading to Scotland on Friday in her first visit as Britain's new prime minister, stressing her bid to maintain UK unity in the Brexit vote fall-out.May was due in Edinburgh for talks with Scottish First Minister Nicola Sturgeon, who has threatened another referendum on Scottish independence following Britain's seismic vote to leave the European Union.May took office on Wednesday after David Cameron stepped down as premier in the wake of the June 23 referendum.She has set about culling his ministers – and stunned world capitals by appointing the often undiplomatic Brexit spearhead Boris Johnson as foreign secretary.The referendum result sent shockwaves around the world and sparked fears of an economic downturn as Britain potentially faces exclusion from its biggest trading market – a key concern for Sturgeon.A majority of voters in Scotland wanted Britain to stay in the EU and nationalist leader Sturgeon sees this as a possible pretext for another independence referendum.Scots voted in September 2014 to remain part of the United Kingdom, which has endured for three centuries.In heading swiftly to Edinburgh, May, the new leader of the centre-right Conservative and Unionist Party, would emphasise her strong support for the union and affirm her commitment to keeping Sturgeon's devolved administration involved in the Brexit negotiations, a Downing Street spokesperson said.May's UK unity concern"I believe with all my heart in the United Kingdom," May said in a statement."This visit to Scotland is my first as prime minister and I'm coming here to show my commitment to preserving this special union."She told Scots her government would "always be on your side"."We are going to build a better Britain and a nation that works for everyone – not just the privileged few," she added.In the June 23 referendum, 52% of voters backed leaving the EU, on a 72% turnout.In Scotland, 62% voted for Britain to stay in, on a 67% turnout."We've got perhaps different views on what should happen now in terms of the Brexit vote," said Sturgeon, who heads the left-wing secessionist Scottish National Party."My job is to seek to protect Scotland's interests," she told STV television.May "has to make the process open and flexible", she added.Morning of the long knivesAfter six years as Cameron's interior minister, May was viewed as a safe pair of hands to replace him, but began with a deep cull of some of her former cabinet colleagues.She sacked long-serving finance minister George Osborne and Brexit-campaigning justice secretary Michael Gove – and gave Johnson the diplomatic brief."Cabinet's Brexit bloodbath" the i newspaper said on Friday."May's radical reshuffle stuns the old guard", said The Guardian's front page.It said May had shown steel, but it would "count for little without clarity" about its purpose.The Times said she had brought "instability at the heart of her cabinet" by bringing in "several explosive egos".Controversy over Johnson's appointment overshadowed the first full day of May's premiership.US President Barack Obama called May to congratulate her on Thursday, but White House spokesperson Josh Earnest offered a tepid response to her choosing Johnson.The "special relationship" between the two countries "transcends any single personality", he said.'Chilling effects' of BrexitUS Trade Representative Michael Froman said Brexit opens new questions for negotiations over an ambitious transatlantic trade treaty.He said he has already contacted London officials over how to organise US trade with Britain outside the EU.European leaders have pressed May to move quickly in implementing Brexit, amid fears of the damage the continued uncertainty could do to the EU and the world economy.New finance minister Philip Hammond warned Brexit was having "chilling effects" on the financial markets and said business investment decisions were being put on hold.The Bank of England on Thursday held off on an anticipated cut in interest rates, keeping them unchanged at 0.50%, but signalled a possible cut next month.Meanwhile the private family funeral of murdered MP Jo Cox was to take place in her hometown constituency on Friday.Cox was shot and stabbed during the referendum campaign, which was suspended as a mark of respect for the "Remain" supporter.