Prince Harry, 33, recently travelled with his wife Meghan Markle, 36, to Dublin on their first overseas visit as a married couple.
The pair are expected to undertake their first official tour to Australia later this year during the Invictus Games, created by Harry.
Harry and Meghan made a number of appearance before their wedding, including to Brixton, Cardiff and Wales.
In 2016, the prince ended his two-week Caribbean tour and was due to fly back to the UK for a number of public engagements.
Yet he ended up breaking royal protocol by seeing Meghan Markle instead.
Prince Harry was booked to fly back on a British Airways flight to London from Barbados, according to Kensington Palace.
Instead, he travelled to Toronto to see Meghan, which is against royal protocol.
According to the Telegraph, palace policy dictates that “working visits should not be combined with personal travel”.
The rule was brought into force in 2004 after Prince Andrew’s antics came under fire.
The royal was lambasted for combining business trips with personal trips including golfing expeditions.
Royal family members official trips are paid for by the taxpayer while personal trips are paid at their own expense.
At the time, the Royal Household said: “In order to avoid confusion, combining private and public engagements in the same trip is actively discouraged.”
Despite this, Prince Harry would have paid for his own ticket to travel to Canada where Meghan was filming Suits at the time.
Prince Harry and Prince William regularly fly on budget airlines for personal trips.
It isn’t the first time the couple have broken royal protocol together.
The pair regularly hold hands at events such as at the Toronto Invictus Games when they are first spotted together as a couple.
Royal family members often refrain from doing so as they are representing the UK on a work trip, and so displays of affection could be considered inappropriate.
Prince William and Kate Middleton are rarely caught holding hands, although on some tours they have been spotted with their arms around each other.
Queen Elizabeth and Prince Philip are also never caught in public being affectionate as they act professionally when on state visits.
Yet while it is an unspoken etiquette advisory, it is not an enforced rule.
At a recent event with the Queen, Harry and Meghan decided against holding hands when at the Your Commonwealth Youth Challenge Reception.
