Now that Donald Trump has arrived in the UK, many will undoubtedly be wondering how the US president will fare while spending time with Her Majesty the Queen.

The Queen has made the acquaintance of almost every acting US president since 1945, starting with Harry Truman whom she met while visiting Washington, DC as a princess in 1951.

There are number of rules that Trump is expected to follow when greeting the reigning British monarch, some of which are more regimented than others.

Earlier today, the president and US first lady Melania Trump arrived at Buckingham Palace for a private lunch and welcome ceremony.

While Trump was likely instructed on how to address the Queen in the appropriate manner, the royal family are apparently more relaxed nowadays with regards to royal protocol than they used to be.

The Queen with US presidents: Truman to Trump Show all 23 1 /23 The Queen with US presidents: Truman to Trump The Queen with US presidents: Truman to Trump Eisenhower President Dwight D Eisenhower welcomes the Queen to Washington on 18 October 1957 AFP/Getty The Queen with US presidents: Truman to Trump Truman President Harry Truman welcomes then Princess Elizabeth to Washington on 4 November 1951 PA The Queen with US presidents: Truman to Trump Eisenhower President Dwight D Eisenhower and the Queen inspect a Guard of Honour at the gates of Balmoral Castle on 28 August 1959 Getty The Queen with US presidents: Truman to Trump Eisenhower President Dwight D Eisenhower with the Queen at Balmoral Castle on 29 August 1959 PA The Queen with US presidents: Truman to Trump Kennedy President John F Kennedy and wife Jacqueline with the Queen and Prince Philip at Buckingham Palace on June 5 1961 PA The Queen with US presidents: Truman to Trump Nixon The Queen and then Vice President Richard Nixon share a laugh at a Thanksgiving Dinner at Winfield House, the US ambassador's residence in London on 27 November 1958 PA The Queen with US presidents: Truman to Trump Nixon President Richard Nixon meets the Queen and Prime Minister Edward Heath at Chequers on 3 October 1970 Getty The Queen with US presidents: Truman to Trump Ford The Queen waves to the crowd as she and Prince Philip are welcomed to the White House by President Gerald Ford and wife Betty Ford on 7 July 1976 PA The Queen with US presidents: Truman to Trump Carter President Jimmy Carter and the Queen at a state dinner at Buckingham Palace on 7 May 1977 PA The Queen with US presidents: Truman to Trump Reagan President Ronald Reagan goes riding with the Queen at Windsor on 8 June 1982 PA The Queen with US presidents: Truman to Trump Reagan President Ronald Reagan riding with the Queen at Windsor on 8 June 1982 PA The Queen with US presidents: Truman to Trump Reagan President Ronald Reagan addresses a banquet at Windsor Castle on 8 June 1982 PA The Queen with US presidents: Truman to Trump Reagan President Ronald Reagan is pictured with the Queen and Prime Minister Margaret Thatcher before a banquet at Buckingham Palace on 9 June 1984 PA The Queen with US presidents: Truman to Trump Bush (H W) President George H W Bush waves to the crowd as he takes the Queen and Prince Philip to a baseball game in Baltimore on 15 May 1991 AFP/Getty The Queen with US presidents: Truman to Trump Bush (H W) The Queen shares a joke with former first lady Barbara Bush as she and former president George H W Bush attend an awards ceremony in London in November 1993 AFP/Getty The Queen with US presidents: Truman to Trump Clinton First Lady Hillary Clinton talks with the Queen at Buckingham Palace on 30 November 1995 AFP/Getty The Queen with US presidents: Truman to Trump Clinton President Bill Clinton and the Queen pose for a photo at the Guildhall in London before a banquet to commemorate the 50th anniversary of the D-Day invasion in 1995 AFP/Getty The Queen with US presidents: Truman to Trump Bush (W) The Queen waves to the crowd as she and Prince Phillip are welcomed to the White House by President George W Bush and wife Laura Bush on 7 May 2007 PA The Queen with US presidents: Truman to Trump Bush (W) President George W Bush and wife Laura Bush with the Queen and Prince Philip on a state visit on 19 November 2003 AFP/Getty The Queen with US presidents: Truman to Trump Obama President Barack Obama looks on as the Queen signs a guestbook after a dinner at Winfield House, the US ambassador's residence in London on 25 May 2011 AFP/Getty The Queen with US presidents: Truman to Trump Obama The Queen and President Barack Obama arrive at a state banquet at Buckingham Palace on 24 May 2011 AFP/Getty The Queen with US presidents: Truman to Trump Obama The Queen and Prince Philip welcome Barack and Michelle Obama at Buckingham Palace on 1 April 2009 AFP/Getty The Queen with US presidents: Truman to Trump President Donald Trump and the Queen inspect a Guard of Honour at Windsor Castle in July 2018 PA

"It isn't as much a case of meeting the Queen, but rather being presented to her (typically by one of her courtiers)," Rupert Wesson, Debrett's academy director, explains to The Independent.

"In this instance, they will likely say: 'Your Majesty, may I present Mr Donald Trump'.

"It is customary for men to bow, however this is a very subtle gesture and not exaggerated - the Queen is said to be quite relaxed about this."

The royal family has outlined the proper way in which to address the Queen, tips that Trump will have to take heed of prior to his visit.

When greeting the monarch for the first time, the president will be expected to call her “Your Majesty”, before then referring to her as “Ma’am”, pronounced in the same manner as “jam”.

While usually men may greet the Queen by bowing to the monarch from the neck and women may do so by giving the royal a small curtsy, on the occasion of the US president's state visit, both he and the first lady shook hands with the Queen.

"The rules are not official or written down but rather an understanding," explains etiquette expert Grant Harrold, former royal butler to Prince Charles.

"President Trump should not offer his hand to the Queen for a handshake but he will have to wait for the Queen to offer the handshake.

"Only then may he accept and he must remember the grip should not be too tight or too loose, and it is two to three pumps then hands go back to your side."

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This evening, Trump will attend a royal state banquet in the Buckingham Palace Ballroom.

The formal occasion will be attended by around 150 guests, who have been invited "on the basis of their cultural, diplomatic or economic links to the country being hosted".

The festivities will begin with a speech and toast delivered by the Queen.

The US president will then respond with a toast in honour of the British monarch.

According to Debrett’s, when dining at a formal meal, guests should refrain from hunching in their chairs, starting the meal before anyone else and talking with their mouths full.

Furthermore, if any speeches are being given during the evening, talking during the oration is considered rude.

In 2017, Canada’s governor general David Johnston appeared to breach royal protocol by making physical contact with the Queen while helping her down a flight of stairs at Canada House in London.

However, while many may have assumed any physical contact with the Queen is strictly off limits in keeping with royal protocol, Michelle Obama’s famous hugwith the monarch proves that this isn’t necessarily the case.