One of the men killed in a helicopter crash in the North was a personal friend of Prince Charles', a spokesperson from his official residence at Clarence House confirmed.
Charles Stisted was chief executive of the exclusive Guards Polo Club in Windsor and was known to the Prince, the Duchess of Cornwall and Princes William and Harry.
Mr Stisted, 47, was one of three people killed when a helicopter came down in a remote site in the Mountains of Mourne in Co Down.
A Clarence House spokeswoman said: “The Prince of Wales, The Duchess of Cornwall, Prince William and Prince Harry are all shocked and deeply saddened by this terrible tragedy.
“Their Royal Highnesses’ thoughts and prayers are with the families of those killed at this dreadful time.”
Mr Stisted, from Windsor Great park in Egham, Surrey in England, is also listed as non-executive director of polo event managing company – The Polo Agency.
It is thought the helicopter was returning to England following a shooting expedition.
The Agusta helicopter was travelling from St Angelo airport in Co Fermanagh where the passengers had been on a hunting trip, but the aircraft crashed at around 4pm on Saturday at the mountainous Leitrim Lodge Picnic area near Hilltown.
Mountain rescue teams, the coastguard and other emergency services were alerted when a member of the public reported seeing an aircraft in distress, but it quickly became clear that no one had survived the impact.
After a lengthy recovery operation police confirmed that the pilot and his two passengers were killed.
The Times newspaper reported that the helicopter’s owner Ian Wooldridge also died in the crash.
A source revealed the downing of the helicopter was being investigated by the Air Accidents Investigation Branch of the Department for Transport.
South Down MP Margaret Ritchie said: “The local community is in absolute shock, but their thoughts are with the families and friends of the victims. Their thoughts and prayers are with them. What should have been a happy occasion has ended in tragedy.”
The Mournes area is internationally renowned for its picturesque scenery. The mountain range, set on the coastline of south Co Down, is designated as an area of outstanding natural beauty.
The highest mountain in the range, Slieve Donard, is nearly 3,000 feet high.