The Duke of Cambridge will continue to carry out royal engagements but is not expected to increase his number of public duties.
The second in line to the throne is in a "transitional" year, sources have said, and is considering options for his "public service", an announcement will be made about his decision within the next 12 months.
The Duchess of Cambridge has made her first public appearance since the birth of her baby as she joined Prince William, starting a charity endurance marathon on Anglesey.
Baby George didn't make the trip, but as his father's time at RAF Valley, and in Wales comes to an end, hundreds of people did turn out to see the couple before they leave Wales for good. Ian Lang reports.
The Duchess of Cambridge's decision to join her husband at the launch of an ultra-marathon today was a surprise and her attendance was only revealed this morning.
The royal couple have lived on Anglesey for years and have always spoken of their love of the island.
William said a public goodbye a fortnight ago as he confirmed his young family would be leaving their Welsh home and moving "elsewhere" when his posting comes to an end this month, having completed his three-year tour as an RAF search and rescue helicopter pilot based at RAF Valley on Anglesey.
The Duke of Cambridge will start the Ring O'Fire Anglesey Coastal Ultra Marathon on Anglesey later. The Ultra Marathon is an annual 135 mile coastal marathon circumnavigating the Isle of Anglesey. The foot race is staged over three days and follows the Anglesey Coastal Path around the island.
Prince William will meet a number of runners and their families and a selection of volunteers involved in the administration of the race before officially starting the Ultra Marathon.
The 135 mile distance and 13,695 feet of vertical ascent makes the Ring O' Fire one of the most extreme ultra marathons in the United Kingdom.