With Prince Louis christened and now almost three months old, the family is believed to be enjoying a sun-soaked holiday on an exclusive Caribbean island.
The trip could also be to celebrate Prince George’s birthday, who turns five on the 22nd July.
According to royal blogger Tea Time with the Cambridges, a website dedicated to all things Cambridge family, the family were spotted arriving at St Lucia airport.
They then reportedly boarded a private plane to take them to their next destination, the small private island of Mustique.
The Middleton family were also said to have been spotted with the Cambridges, embarking on the ultimate family getaway.
It is unknown if Pippa Middleton and James Matthews were with the family, but it could well be possible with Pippa’s baby not due for a few more months.
Despite the reported sightings, Kensington Palace has declined to comment, but Twitter is rife with news that family is now on the private island.
The couple has no public engagements scheduled until 8th August, giving the family some time to relax, unwind and keep out of the public eye.
Is it the first holiday Kate and William have taken with Prince George, Princess Charlotte and Prince Louis.
Mustique is a luxurious, unspoilt private island in St Vincent & the Grenadines, known for its royal and celebrity visitors.
The island is owned by the Mustique Company, which is in turn owned by the island’s homeowners.
With around 100 villas the population is small, acting as a perfect hideaway for high-profile holidaymakers.
It also operates a no-fly zone, meaning pictures of the family holidaying are highly unlikely.
The holiday comes after a busy few weeks for Kate and William, with Prince Louis’ christening and a host of royal engagements undertaken.
This is not the couple’s first time on the private island, being spotted in 2015 four months before Princess Charlotte’s birth.
Kate’s parents Carole and Matthew usually visit the island earlier in the year for some winter sun, but may have held off this year to spend it their holiday the whole family.
They also stayed on Mustique when Kate was pregnant with Prince George back in 2013.
Kate is still supposedly on maternity leave after giving birth to Prince Louis on 23rd April this year.
It is still unconfirmed when the Duchess will be out of maternity leave, but returned to work four months after Princess Charlotte was born.