Queen Elizabeth
Queen Elizabeth's actual birthday is on 21 April. REUTERS/Suzanne Plunkett

She may have already turned 89 in April, but this weekend (13-14 June) the Queen will celebrate her birthday with an annual extravaganza called Trooping The Colour.

What is it and when did it start?

Trooping The Colour, also known as the Queen's Birthday Parade, is essentially the state's birthday bash for the reigning monarch. It has taken place in London since 1820.

Where/when do the celebrations take place?

It takes place on Horse Guards Parade near London's St. James's Park on 13 June.

Where can I watch it?

If you want to enjoy the festivities, you can watch along The Mall or from the edge of St. James's Park for free. Make sure to arrive well before events begin at 10.00am to guarantee you get a good view. Alternatively, tune in to BBC 1 to watch the parade broadcast live.

What happens on the day?

The spectacular event is a master class in military pageantry and is carried out by fully trained and operational troops from the Household Division of the British Army. The ceremony kicks off with the Queen being escorted by a royal procession of mounted troops and horse guards down The Mall from Buckingham Palace, before carrying out an inspection.

She will finish the ceremony by joining the rest of the royal family to watch a flypast from the RAF.

Who will attend?

It is typically watched by royal family members, invited guests and members of the public.

Key members of the royal family are expected to take part in the ceremony with Prince Charles, Prince William and Princess Anne riding on horseback in the parade as royal colonels, and the Duke of Edinburgh, Duke of Kent and other members riding in carriages.

It had been previously reported that the Duchess of Cambridge would be ending her maternity leave in time for the Queen Elizabeth's birthday parade. It would be her first public engagement since giving birth to Princess Charlotte on 2 May.

An insider told OK! Magazine: "It's a huge public event, an incredible pageant carried out by the Queen's personal troops. Kate will be on show for it, dressed up in a smart outfit, with the eyes of the world on her."

So do not be surprised if the mother-of-two makes an appearance.

Is there a dress code

If you are lucky enough to have bagged a ticket to attend the event, make sure to opt for smart casual attire on the day. No denim allowed.

Has the Queen ever been a no-show?

Elizabeth II has missed the Trooping The Colour presentation just once during her time on the throne, when a 1955 national rail strike led to the event being cancelled.

Do we get a day off?

The Trooping of The Colour is not a national holiday in the UK. However, some Commonwealth nations (such as Australia and New Zealand) get a public holiday on her official birthday.