WESTERN ideals of individualism, opportunity and free political development will “prevail in the long run,” Boris Johnson has insisted as he made clear Global Britain needed the clear leadership of Theresa May to navigate it through an age of uncertainty.

Speaking at the Lord Mayor’s Banquet at Mansion House in London, the Foreign Secretary argued: “The last two decades have been broadly good ones for the world; a billion people have been taken out of poverty and the goal of halving extreme poverty by 2015 was reached five years early.”

But he warned that these were “uncertain and unstable times” and that Britain needed to “help manage them in a serious and clear-sighted way”.

He went on: “In recent years we have seen an increase in the global tally of deaths from wars. We and our allies face threats from countries with a nuclear weapons capacity and from those trying to acquire that capacity.

“For the first time for many years, some countries are trying to change European borders, not by agreement, but by force. And, as we have seen across Europe in recent months, we face a continued battle against terrorism and the hateful ideology of Islamic extremism. These are uncertain and unstable times.”

The Secretary of State defended the Western ideals of individualism, of opportunity and of free political development, saying they were the “right ones” that would "make the world better and so will prevail in the long run". But he noted that they would “not do so unless we stand up for them and act accordingly”.

Turning to the election at home, he said: “That is where leadership comes in. Clear leadership to navigate this age of uncertainty. We are determined to provide that leadership, to give people the security and certainty they need.

“Because there can be no more important task for a government than to keep people safe and we must be prepared to do everything necessary to do so.

“It is why the Prime Minister made it a priority when she took office last year to ensure the renewal of Britain’s crucial independent nuclear deterrent and to lead the debate in Parliament.

“It is why she made it clear in the US earlier this year that Britain saw our profound security and defence alliance with the US as part of the bedrock of global security in the modern world.”

Meantime, Conservative HQ denied that Mr Johnson was being sidelined from the party's election campaign by Mrs May.

Reports have suggested the Foreign Secretary had been told to keep a low profile because he was vulnerable to challenge over his pre-referendum claims that Brexit would deliver £350 million a week to spend on the NHS.

A senior Conservative source dismissed the claims as speculation and said the Cabinet minister would soon enter the fray.

"The Foreign Secretary will have a clear role to play," declared the source. "You will see him in a prominent role in the very near future."

Since abandoning an expected challenge for the Tory leadership following last year's vote, Mr Johnson has been the occasional butt of the PM's wit.

In her speech to last year's annual Conservative conference, she made a joke at his expense, asking: "Can Boris Johnson stay on message for a full four days?"