They marched from Trafalgar Square towards Buckingham Palace, where Mr Trump and other Nato leaders are being hosted by the Queen tonight.

Many in the crowd held placards bearing messages such as ‘No to Trump, No to War’ and ‘Trump, Hands off our NHS’.

A number of protesters expressed their fears over the impact of a future trade deal between the US and the UK on the NHS.

Raoul Li-Everington, 27, a junior doctor working for the NHS in north London, said the health service was in ‘decline’ due to ‘austerity’ policies.

‘That only leads to universal coverage not existing anymore.

‘People will have poorer care and we will inherit a lot of America’s health problems in terms of their system.

‘I’m here on behalf of all the junior doctors in this country worried about the path the NHS is heading down, which is depressing.’

Dave Bell, 66, from London, who worked as a mental health nurse for 45 years, said he feared the NHS being ‘broken up’ by private organisations.

He added: ‘Health is not a commodity to make a profit on and that’s exactly what’s happening in America.’

Police allowed protesters to make their way down The Mall on Tuesday night as official cars with police escorts sped past on the other side of the barriers.

A group of protesters carrying flags and banners called on Nato and Turkey to stop their ‘war on Kurds’.

Others in the crowd said they were protesting against the Nato gathering in London.

Sue Roebuck, 73, from London, said: ‘I think Nato is a warmongering organisation, it’s not there for peace at all.’

‘It’s all about militarising the whole world.’