Sailors on deployments around the world celebrated the birth of the royal baby.
Ships, at home or at sea, are flying the Royal Navy Ensign from their main masts to mark the arrival of the prince.
The ship’s companies of Portsmouth-based frigates HMS Kent and HMS Lancaster also added their own congratulations by spelling out the word ‘boy’ on their flight decks.
HMS Kent is currently on operations in the Middle East, and HMS Lancaster is deployed on a patrol task in the Caribbean.
HMS Lancaster’s commanding officer, Commander Steve Moorhouse, said: ‘HMS Lancaster sends their warmest congratulations and best wishes to the Duke and Duchess of Cambridge.’