Sources explain that Princess Kate and Prince William are experiencing the "toughest year of their lives together"

The Princess of Wales has returned to public duty this summer, making her first public appearances since her cancer diagnosis earlier this year.

The 42-year-old is said to be making “good progress” in her recovery, attending both the Trooping the Colour parade in June, and the Wimbledon Gentleman's Singles Final in July, even making a video cameo as part of the Olympic Games closing ceremony last week.

However, despite these positive signs, Princess Kate has made it clear that she is not yet out of the woods. And for the next few months, the Princess of Wales is expected to continue "living under the radar" as she completes her treatment. In fact, some experts have reported that we might not see a full return from Princess Kate until 2025.

Sources spoke about this recently, impressing upon the Daily Mail's Rebecca English that it's been "a really difficult year for the entire family" and that Princess Kate and Prince William were experiencing the "toughest year of their lives together."

"I don’t think people realise how much she has gone through behind the scenes and for how long, far longer than anyone actually appreciates," explained one source.

Another added: "She’s an incredibly strong woman, but she really has been through the wars. Her treatment and recovery is still a priority and will be ongoing for some time to come."

It is not known when the Princess of Wales will return to her royal duties on a permanent basis, but she has asked the public for "time, space and privacy" while she recovers.

"I have been blown away by all the kind messages of support and encouragement over the last couple of months," Princess Kate announced in a public statement on her health earlier this year. "It really has made the world of difference to William and me, and has helped us both through some of the harder times.

"Thank you so much for your continued understanding," she later added. "And to all of you who have so bravely shared your stories with me."

We will continue to update this story.