Meghan Markle and Prince Harry celebrate their fourth anniversary with Archie and Lilibet

Prince Harry and Meghan Markle are celebrating their fourth anniversary today with a low-key family-only affair.

The Duke and Duchess of Sussex, who tied the knot in a lavish ceremony at St George's Chapel in Windsor four years ago,  will mark  the day with their kids at their Montecito home.

 Royal expert Duncan Larcombe claims that, to mark the occasion, Harry and Meghan will make their kids the "priority" rather than hosting an extravagant party.

This year marks the third time the couple will celebrate their anniversary in the US, and any celebrations will likely be limited to just the couple and their children – three-year-old Archie, and Lilibet, who turns one next month.

"It's amazing really that four years ago there were nearly two billion people watching as they got married in the wonderful fanfare. And here they are four years on very, very isolated. Meghan isn't speaking to anyone in her family apart from her mum," the royal expert told OK! Magazine.

He continued: "When you've got kids they are the priority. So I think you'd expect them to mark the day as a family alone rather than having a big party or anything like that."

He continued: "When you've got kids they are the priority. So I think you'd expect them to mark the day as a family alone rather than having a big party or anything like that."