The Duke of Cambridge will return to his former RAF base with the Duchess to attend a ceremony marking the end of RAF Search and Rescue (SAR) Force operations.
A disbandment parade will be held at RAF Valley on Anglesey on Thursday to formally commemorate the end of 75 years of service by the men and women who over the decades have often put their lives at risk to save others.
The service has been privatised and is now operated by civilian company Bristow Helicopters after it was awarded a contract by the Department for Transport in 2013.
The Cambridges were just another forces couple when they moved to Anglesey in Wales after the future Commander-in-Chief of the Armed Forces joined C Flight, 22 Squadron at RAF Valley in September 2010.
William served a three-year tour with SAR and during his time qualified as an operational captain taking overall control of the Sea King helicopters,
During his time at RAF Valley, The Duke - known as Flight Lieutenant Wales - undertook a total of 156 search and rescue operations, resulting in 149 people being rescued.
Born of lessons learnt from the Battle of Britain, SAR's predecessor, the Directorate of Air Sea Rescue (ASR), was formed at the headquarters of RAF Coastal Command in 1941.
ASR's mandate was to form a combined and effective rescue service for downed allied aircrew that were being lost at an alarming rate in the seas around Britain.
Since its inception tens of thousands of lives have been saved by the men and women of ASR and SAR, operating from marine craft, fixed-wing aircraft and helicopters.
They have been assisted in this task by HM Coastguard since 1971.