The British Prime Minister will set out her response to the global changes signalled by Donald Trump's election victory in her first major foreign policy speech amid tensions about Nigel Farage's close links to the president-elect.
Theresa May will use an address in the City of London to say that the UK can seize the opportunities presented by Brexit and the US election to become a global leader on free trade, "doing business with old allies and new partners alike".
But European divisions about Mr Trump's election victory were underlined as Brussels foreign policy chief Federica Mogherini dismissed Boris Johnson's absence from a meeting of EU ministers by saying it was "normal" for a country leaving the bloc "not to be so interested" in the future of EU-US relations.
Arriving in Brussels for a regular meeting of EU foreign ministers, Mr Johnson said the election of Mr Trump represented a "moment of opportunity" for Britain and for Europe.
"I think there is a lot to be positive about and it is very important not to prejudge the president-elect or his administration," he said.
"It's only a few days since the election has taken place. I think we all need to wait and see what they come up with. But I think we should regard it as a moment for opportunity.
"Donald Trump is a dealmaker and I think that could be a good thing for Britain, but it could also be a good thing for Europe and that I think is what we need to focus on today."
Mrs May will use her speech at the Lord Mayor's Banquet to say the UK is uniquely placed to provide leadership in the transformed modern world.
She will say that the UK will not be "standing inflexibly, refusing to change and still fighting the battles of the past, but adapting to the moment, evolving our thinking and seizing the opportunities ahead".
"That is the kind of leadership we need today. And I believe that it is Britain's historic global opportunity to provide it," Mrs May will say.
But she will also acknowledge the anti-globalisation sentiments that helped fuel the victories of both Mr Trump and the Brexit campaign.
Mrs May will say that the UK can "show the world that we can be the strongest global advocate for free markets and free trade because we believe they are the best way to lift people out of poverty ... but that we can also do much more to ensure the prosperity they provide is shared by all".
She will say: "To be the true global champion of free trade in this new modern world, we also need to do something to help those families and communities who can actually lose out from it."
Following high-profile corporate scandals such as Sir Philip Green's sale of BHS, Mrs May will say the UK can "demonstrate that we can be the strongest global advocate for the role businesses play in creating jobs, generating wealth and supporting a strong economy and society" but "we can also recognise when a minority of businesses and business figures appear to game the system and work to a different set of rules, the social contract between businesses and their employees fails - and the reputation of business as a whole is quickly undermined".
The election of Mr Trump has presented Number 10 with a diplomatic headache as Mrs May has come under pressure to take advantage of the access that interim Ukip leader Mr Farage has to the president-elect.
Number 10 has insisted that Mr Farage will have no role to play, but Tory peer and former trade envoy Lord Marland said Downing Street should use Mr Farage as a "salesman".
After pulling off the political coup of becoming the first British politician to meet Mr Trump since his election win, Mr Farage hinted ministers are sounding him out about dealing with the president-elect as he revealed the Republican victor's close advisers have "reservations" about Mrs May's government.
Mr Farage disclosed that members of the president-elect's inner circle were concerned about unflattering comments made by British Cabinet ministers, though Mr Trump told him he had a "nice" phone call with Mrs May.
"He said he had a nice conversation, although some of his team had reservations about what members of the Cabinet have said during the election. Believe you me, his team are conscious of the comments," Mr Farage told The Daily Telegraph.
The pair met at Trump Tower in New York and spent over an hour discussing the president-elect's victory, global politics and the status of Brexit, according to Ukip.
The EU's response to Mr Trump's election was to convene an emergency meeting of foreign ministers - which was snubbed by Mr Johnson.
Ms Mogherini barely concealed her frustration at the situation, telling reporters: "Some in Europe are surprised not when that country is absent, but nowadays that it is still present around the table of the 28.
"So, I guess it is only normal for a country that has decided to leave the European Union not to be so interested in our discussions on the future of our relations with the United States."