Trooping the Colour is always a major highlight of the royal calendar.

Each June, the royal family are out in force, taking part in the carriage procession, watching the military parade on Horse Guards Parade and gathering on the Buckingham Palace balcony to enjoy a celebratory flypast.

The royals gather on the balcony for the celebration in 2019. Credit: Yui Mok/PA

It marks the monarch’s official birthday and has done since 1748.

The display of pomp and pageantry usually attracts thousands of tourists who flock to central London to see the traditional spectacle.

Crowds after watching a flyover after Trooping. Credit: Johnny Green/PA

It has only been cancelled once before during the Queen’s reign – in 1955 during a national rail strike.

But restrictions during lockdown have prevented the celebration from taking place in 2020 in its regular form.

The Queen and Philip stand on the podium at Horse Guards Parade in 2008. Credit: John Stillwell/PA

Instead, the Queen, who has been staying at Windsor with the Duke of Edinburgh for the past 12 weeks, is taking two royal salutes at the castle from the Welsh Guards – under social-distancing rules with no spectators.

When she was five, Princess Elizabeth rode in a carriage with her grandmother Queen Mary and mother the Duchess of York on her way to Trooping, and joined them on the balcony afterwards.

Queen Mary, Princess Elizabeth and the Duchess of York travel to the Trooping of the Colour celebrations in 1931. Credit: PA

She first appeared mounted as Colonel of the Grenadier Guards riding side saddle in 1947 at the first birthday parade to be held after the Second World War.

Princess Elizabeth behind her the father King George VI in 1947. Credit: PA

She took the royal salute in 1951, when she deputised for her ill father.

She became Queen in 1952 and has continued receiving the mark of respect every year except during the strike of 1955.

Princess Elizabeth standing in for her father in 1951. Credit: PA

In 1981, a teenager fired six blank shots in her direction as she made her way along The Mall.

Her horse Burmese was startled, but the Queen managed to regain control and carried on.

The Queen calms her horse Burmese while policeman spring to action after shots were heard as she rode down the Mall. Credit: PA

Burmese was the Queen’s favourite steed for Trooping and ceremonial occasions – and this week the equestrian-loving monarch picked the black mare as one of her favourite horses of all time for a list for Horse & Hound magazine.

She used Burmese, which was a gift from the Royal Canadian Mounted Police, for 18 years from 1969 to 1986 until the animal was moved to Windsor for retirement.

The Queen then decided that, rather than train another charger for the ceremony, she would in future be driven in a carriage.

The weather has not always been in her favour. In 2001, she was pictured in her carriage holding an umbrella and dressed in a waterproof coat to protect her from the rain.

The Queen with an umbrella and a waterproof coat during a rainy carriage procession to Trooping in 2001. Credit: Michael Stephens/PA

More than 1,400 soldiers, 400 musicians and 200 horses usually take part in the traditional display.

The troops participating in the march past are drawn of fully trained, operational troops from the Household Division.

The streets are lined with crowds waving flags as the parade moves from Buckingham Palace and down The Mall to Horse Guards Parade.

The Queen waving to the crowds on her way to the parade ground in 2018. Credit: Pete Summers/PA

The Queen is greeted on Horse Guards with a royal salute and carries out an inspection of the troops.

The Queen’s Colour of a battalion of Foot Guards is ‘trooped’ – carried along the ranks – before the sovereign.

Only one colour can be trooped at a time, and the five Household Regiments – Grenadier, Coldstream, Scots, Irish and Welsh Guards take their turn each year.

The Duke of Cambridge, the Prince of Wales and the Duke of Kent leave Buckingham Palace to attend Trooping in 2012. Credit: Dominic Lipinski/PA

Other members of the royal family usually ride as part of the parade including the Prince of Wales, the Princess Royal, the Duke of Cambridge and the Duke of Kent in their role as royal colonels, as well as previously the Duke of Edinburgh.

The Duke of York has taken part on horseback as Colonel of the Grenadier Guards, but now no longer carries out royal duties after the fall out over his Newsnight interview about his friendship with convicted sex offender Jeffrey Epstein.

Royal children including Prince George, Prince Charlotte and Prince Louis often join their parents on the Palace balcony to watch the RAF flypast.

The Cambridges on the Palace balcony in 2019. Credit: Victoria Jones/PA

Trooping the Colour originated from traditional preparations for battle.

Colours, or flags, were carried or “trooped” down the ranks so they could be seen and recognised by the soldiers as they were used as rallying points in the confusion of fighting.

In the 18th century, guards from the royal palaces assembled daily on Horse Guards to “troop the colours”, and in 1748 it was announced that the parade would also mark the sovereign’s official birthday.