Every time Prince Harry played the third-wheel in Prince William and Kate's relationship: see pictures

With less than a week to go before this year's Trooping the Colour, all eyes will be on newlyweds Prince Harry and Meghan Markle! The couple, who tied the knot last month in a beautiful ceremony, will make their first appearance alongside the Queen as well as the Duke and Duchess of Cambridge on the iconic balcony at Buckingham Palace. In honour of this milestone, we take a look back the best moments Harry played the role of third wheel in Prince William and Kate's relationship at royal engagements.

MORE: Prince Harry and Kate's sweet sibling bond

There's no denying that the 33-year-old has a close bond with his older brother and his wife, often doing public duties together as a threesome. The famous trio, who have welcomed Meghan into the fold and are now dubbed 'the fab four', are the forces behind their mental health campaign, Heads Together, and have since attended various events together to promote their charity. Royal engagements aside, Harry has also been pictured with the beloved couple at friends' weddings and multiple sporting events, including the Six Nations Championship in 2007 and during the London 2012 Olympic Games. The Duke of Sussex even managed to play fifth wheel when Michelle and Barack Obama visited in the UK in 2016, with all of the royals taking part in a photocall with them.

See every outfit Duchess Kate has worn to Trooping The Colour

This picture sees Harry in his own little world as he watched the fly past from the balcony of Buckingham Palace during the Trooping the Colour in 2014. William and Kate could be seen sharing a sweet moment together -three years after they shared a kiss on their wedding day.

Prince Harry appeared a little bored whilst watching the action during the RBS Six Nations Championship match between England and Italy in 2007. The Duke and Duchess of Cambridge appeared to be in great spirits whilst chatting between themselves.

During the London Olympics in 2012, William and Kate were in a fit of giggles as they shared a private joke underneath their umbrella. Harry played gooseberry as he sat alongside them without with his own brolly trying to listen in.

Two years later, Prince Harry accompanied Prince William and Kate to the Tower Of London's Ceramic Poppy installation to commemorate the 100th anniversary of the outbreak of First World War. The Duke and Duchess of Cambridge were seen talking, whilst Harry trailed quietly behind them.

In 2016, Prince Harry was made fifth-wheel when Michelle and Barack Obama paid a visit to the UK. The British royals all took part in a photocall - and it seemed that Harry was a little left out.

Last year, at the 2017 Virgin Money London Marathon, Prince William was seen touching his wife's back gently as he guided her along the pathway, while Prince Harry mirrored his brother by doing the same to his back.

In October, the Duke and Duchess of Cambridge as they shared a sweet moment at the Coach Core graduation ceremony at the London Stadium - but Prince Harry was left lingering on his own.