Theresa May vows to 'build a better Britain' as she puts defence of Union at heart of her government

As the new Prime Minister removed the old guard from the Cabinet, one of the most surprising moves was the elevation of Boris Johnson as foreign secretary.

READ MORE: World reacts to Boris Johnson's appointment as Foreign Secretary

George Osborne “resigned” from government after six years at the Treasury and has been replaced by Philip Hammond, regarded as a safe pair of hands, who has long coveted the job of chancellor.

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Mr Osborne’s departure following that of David Cameron with no sign yet of Michael Gove getting a top job, means the influence of the so-called Notting Hill set looks over.

Amber Rudd, a leading Remainer, who performed strongly during the referendum TV debates, is the new home secretary, among whose tasks will be cutting net migration from record highs.

But the key development has been the appointment of a trio of committed Leavers to senior outward-looking roles, underlining Mrs May’s pledge that “Brexit means Brexit”.

David Davis, who lost to David Cameron in the Tory leadership battle in 2005, and who was a prominent Outer, has been appointed secretary of state to lead on the complicated negotiations for the UK’s departure from the EU; the so-called Brexit minister.

Another leading Leaver Liam Fox, who resigned in 2011 as defence secretary over claims he allowed a lobbyist too much access to the Ministry of Defence, makes a return to the front line as international trade secretary.

Fellow Scot, Michael Fallon, remains at the Ministry of Defence, where he has been secretary of state since July 2014; he is said to love the job.

Today, Mrs May will continue making appointments and it is expected that David Mundell, the Tories’ only Scottish MP, will continue at the Scotland Office, where he has been in post since 2010.

As only the second female premier began the process of forming her new government, Mr Johnson, whose ambition to become PM was destroyed by the intervention of Michael Gove, emerged from behind the famous black door, to stroll nonchalantly down Downing Street, wave at the TV cameras and then slip into the back of a black limousine.

Read more: First Minister Nicola Sturgeon: New Prime Minister Theresa May must protect Scotland's place in European Union

Until Britain leaves the EU, the 52-year-old politician will be engaged frequently in trips to Brussels for talks with his European counterparts.

Earlier this year, he ignited a ferocious row after he referred to US President Barack Obama as part-Kenyan. In 2002 in a newspaper column, he also described black people as “piccaninnies” with “watermelon smiles”.

Six years later, he apologised when he was running to become the mayor of London. Last night, supporters defended Mr Johnson’s record saying that he had wide diplomatic experience, noting how in his previous role he had travelled the globe drumming up trade deals for London.

During a day of high drama at Westminster, Mr Cameron was given a standing ovation by Conservative MPs as he made his Commons farewell with the comment "I was the future once"; a self-deprecating reminder of the jibe he directed at Tony Blair as the fresh-faced new Tory leader in 2005.

The outgoing premier was accompanied by wife Samantha and children Nancy, Elwen and Florence as he left No 10 for the last time as Prime Minister in scenes reminiscent of when Gordon Brown departed Downing Street after the 2010 General Election.

In his final prime ministerial statement outside the famous black door, Mr Cameron said he believed he was leaving the country "much stronger" and the economy "immeasurably stronger" after six years in office.

In a clear bid to define the legacy that he will leave behind him, he spoke of his pride at achievements including reducing the deficit, legalising gay marriage, boosting employment, introducing the National Living Wage, increasing international aid spending and cutting waits for NHS treatment in England.

He also paid tribute to his wife Samantha, whom he described as "the love of my life," who had "kept me vaguely sane".

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The former Tory leader said Mrs May would provide "strong and stable leadership” and wished her well in negotiating "the best possible terms for Britain's exit from the European Union".

He then led his children and his wife to waiting cars, waved to the gathered staff and media on the pavements and left for Buckingham Palace.

An hour or so later, his successor, Britain’s 54th prime minister, was in Downing Street, setting out her vision for government, placing the defence of the Union at its heart.

Emphasising the full name of her party, the Conservative and Unionist Party, she declared: “That word Unionist is very important to me. It means we believe in the Union; the precious, precious bond between England, Scotland, Wales and Northern Ireland.

"But it means something else that is just as important; it means we believe in a Union not just between the nations of the United Kingdom but between all of our citizens, every one of us, whoever we are, and wherever we're from."

Stressing how she would lead a One Nation government, the 59-year-old leader said following the EU referendum Britain faced a time of great national change but that the country would rise to the challenge.

"As we leave the European Union we will forge a bold new positive role for ourselves in the world and we will make Britain a country that works not for a privileged few but for every one of us. That will be the mission of the Government I lead and together we will build a better Britain."

Earlier, Nicola Sturgeon, said she wanted a constructive relationship with the new PM but has made clear that “Remain means Remain” as far as Scotland is concerned and that she will do everything in her power to keep the nation in the EU.

READ MORE: World reacts to Boris Johnson's appointment as Foreign Secretary

While she stressed she would look at “all options” to protect Scotland’s interests, the First Minister has made clear that if the nation is forced out of the Brussels bloc against its will, then a second independence referendum is on the table and "highly likely".

Ms Sturgeon is expected to speak to Mrs May later today.

The new PM’s staunch defence of the Union came as this morning a group of senior cross-party politicians, the Constitution Reform Group, launches a bid to create a federal UK to stave off what it sees as the threat of Scottish independence with the publication of a new Act of Union Bill.