Many in Downing Street felt that they had found a friend in Donald Trump four years ago.
The new US leader was an ardent Brexit fan with a dislike of Europe, a billionaire with businesses in the UK – and it was hoped he would cement an even stronger “special relationship”.
Such a partnership would have softened some of the UK’s economic chaos caused by Brexit, as Trump wanted bilateral free-trade deals.
But since his rise to power, Britain has endured a chaotic relationship with him and with America as a result.
He openly attacked Theresa May when she was PM, accused British spooks of spying on him, claimed that this country had “no-go areas” and retweeted three inflammatory videos from a UK far-right group.
But while he is a great admirer of Mrs May’s successor Boris Johnson, his US election rival certainly is not.
Joe Biden has described the Prime Minister as “a physical and emotional clone” of Trump. He opposed Brexit and, due to his Irish heritage, has expressed concern about its potential impact on Ireland’s economy and Northern Ireland’s security.
As America today elects its next leader, we look at what four more years of Trump or a new Biden administration could mean for Britain.
Trump has put America’s post-war allies such as the UK, France, Canada and Germany behind Russia and North Korea.
Trump is not expected to move away from this policy.
He has repeatedly threatened to pull America out of NATO.
If re-elected, he would push harder for the fall of the deal Iran agreed to restrict its nuclear ambitions. Britain would come under more pressure to break away from European allies or risk tougher US sanctions that apply indirectly to British banks and businesses.
A Biden presidency would be more aligned to the UK Government in terms of world affairs. His views on Russia, North Korea and China are in line with Boris Johnson’s government and Biden has suggested he would “rejoin the [Iran nuclear] agreement”.
If Biden wins, the US will be less hostile towards international organisations Britain values, such as the United Nations and NATO.
America would try to repair its damaged global partnerships.
Transatlantic relations would become more straightforward and less unpredictable.
No policies present more opposite stances than Trump’s and Biden’s on climate.
Next year Britain hosts a UN summit where it is hoped the world will set new carbon reduction targets. Trump, who pulled the US out of the Paris climate accord, is unlikely to help – instead pushing America’s use of fossil fuels above renewable energy.
He has rolled back hundreds of Obama-era laws designed to protect nature and will continue to do so.
He has promised to rejoin the Paris Accord and push for even more ambitious targets.
For him, the UN summit in Britain will be an opportunity to promote the idea that he will lead America to play
a large part in tackling global climate change.
The former Vice President is very much aligned with the UK Government views on global warming and CO2 emissions.
He has vowed to ensure that nations come together to help protect the Earth.
An ardent Brexiteer and vocal critic of the EU, Trump revels in Britain’s departure from the European Union.
He has vowed to undertake a “big beautiful” trade deal with Britain. But there are concerns. If the UK does not accept American meat, raised with lower welfare standards, the US could ban exports like Scottish salmon.
Biden and his team are unlikely to have forgotten the disrespect shown by Boris Johnson, when he was Mayor of London, towards Barack Obama.
Democrats believe Brexit was a mistake and have difficulty understanding why Johnson has rated Trump so highly.
Much will depend on whether Britain strikes a free trade deal with the EU that would cancel the need for Johnson’s Internal Market Bill, currently going through Parliament, and which US Democrats believe could undermine the Good Friday Agreement. Biden has so far failed to express thoughts on the UK accepting America’s chlorine-washed chicken or hormone-raised beef.
The parents of British teen Harry Dunn, above left, killed in a road accident allegedly by US former spy Anne Sacoolas, above right, before she fled back to the States, have been robbed of justice under the Trump administration.
His government has refused an extradition request saying their decision is final. During one visit to the States, Trump tried to hijack Harry’s parents by having Sacoolas waiting in another room as they visited the White House. They rejected the opportunity to meet with their son’s alleged killer.
Although the issue is mired in legalities, a Biden administration would give renewed hope to Harry’s family that justice could be served.
The former VP is known for his compassion and has already been approached by Harry’s mum Charlotte Charles to reverse Trump’s decision not to send Sacoolas back to the UK to face trial.
Trump will insist the NHS pays more for American drugs after Brexit as the price of any free trade deal, it has been claimed.
He has repeatedly shown he puts American corporate interests first and rewards US drugs firms, who demand he should seek to open up the UK market.
Britain currently caps the price of drugs used by the NHS, which means US pharmaceutical firms have to sell their drugs more cheaply here.
Trump has tired of Americans having to pay extortionate prices and has vowed other countries will meet the shortfall.
Biden may be a blessing to the NHS as he repeatedly attacks America’s Big Pharma and pushes for universal health care for all.
He is a vocal critic of the States’ healthcare and vowed to build upon Obamacare to help reduce the cost of medicine and treatment.
What may also be beneficial for the NHS is, while a trade deal is a crucial concern for London, he may not devote sufficient time and political impetus to the process to ensure a speedy agreement there prolonging any impact to the NHS.