William and Harry's relationship has 'forever changed' since royal split

Prince Harry and Meghan Markle are back in Canada with their ten month old son, baby Archie Harrison, after a brief return to the UK for their final engagements as senior royals.

The Sussexes attended events, talks and official meetings during their time back in London, and while it was reported that the Queen was upset about their decision not to bring Archie with them, it was later confirmed that this is the real reason they left him behind this time.

While they are said to be 'enjoying the quiet life' overseas, Harry's relationship with his brother, Prince William, has been under intense scrutiny since he decided to step away from royal life earlier this year. When they met in public at the Commonwealth service earlier this month, fans of both the Sussexes and Cambridges took to Twitter to discuss the 'icy' greeting.

Royal biographer Ingrid Seward, who knew their mother, the late Princess Diana, has said: 'One thing Diana said was, "Please, whatever happens, remember you always have each other, and I want you always to stick together." And clearly that can’t happen for a long time.'

An insider has now told PEOPLE: 'They won’t get back to the way they were. Harry is looking straight ahead at his future with his family.'

They also added that Harry is 'not looking back' after moving to Canada with Meghan and Archie.

In their initial statement announcing their decision to step back, the couple said that going forward they would be splitting between the UK and North America. They have since spent their time in Canada, but are expected to return in the summer for Trooping the Colour and to spend time with the Queen at Balmoral.

It is unclear whether the Cambridges will take a trip to the monarch's Scottish estate at the same time.