The Queen has hosted US President Donald Trump at a reception for Nato leaders at Buckingham Palace.

The controversial American billionaire-turned-politician, who was joined by his wife Melania, gathered with Western politicians and their partners in the royal residence’s grand State Rooms on Tuesday evening.

The leaders arrived at the Grand Entrance to the palace before being escorted inside, where they were met by the Queen, the Prince of Wales and the Duchess of Cornwall in the Music Room.

Charles and the monarch then joined the politicians for a group photograph in the Throne Room before they were served drinks in the Green Drawing Room.

The Prince of Wales and the Duchess of Cornwall meets US President Donald Trump and wife Melania at Clarence House, central London, as Nato leaders gather to mark 70 years of the alliance
The Prince of Wales and the Duchess of Cornwall with US President Donald Trump and wife Melania (Victoria Jones/PA)

The Queen, who was wearing a matching jacket and dress in steel blue and teal with teal diamante embellishments and the Queen Mother’s Palm Leaf brooch, spent time at the reception speaking to female leaders and first ladies including Melania Trump and German Chancellor Angela Merkel before mingling with the rest of the leaders and their wives.

Mr Trump could be seen speaking to French President Emmanuel Macron while Prime Minister Boris Johnson was also in attendance.

The royals were out in force for the event, including the Duchess of Cambridge, the Princess Royal, the Duke and Duchess of Gloucester and Princess Alexandra.

The Duchess of Cambridge during the reception in Buckingham Palace as Nato leaders gather to mark 70 years of the alliance
The Duchess of Cambridge during the reception (Yui Mok/PA)

The Duke of Cambridge is away in the Middle East and the Duke and Duchess of Sussex are on a six-week break from royal engagements.

Outside, hundreds of protesters led by NHS workers and anti-war activists had gathered in Trafalgar Square before marching towards Buckingham Palace to protest against Nato and Mr Trump.

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

Protesters in Trafalgar Square, London
Protesters in Trafalgar Square (Isabel Infantes/PA)

Mr Trump received a ceremonial welcome and a banquet at Buckingham Palace during his state visit to the UK in June.

The American leader was met by tens of thousands of protesters in London before he attended a D-Day commemoration service in Portsmouth.

He later boasted about having “automatic chemistry” with the Queen, and praised her as a “spectacular woman”.

Nato – the North Atlantic Treaty Organisation – was established in Washington on April 4 1949.

Leaders of Nato alliance countries and its secretary general join the Queen and the Prince of Wales for a group picture during a reception in Buckingham Palace
Leaders of Nato alliance countries and its secretary general join the Queen and the Prince of Wales for a group picture during a reception in Buckingham Palace (Yui Mok/PA)

It began as a 12-member alliance to counterbalance the growing military might of the Soviet Union and to keep the peace in post-war Europe.

The political and military alliance now has 29 member countries.