Among those in attendance was PSNI Detective Chief Inspector John Caldwell who made his first public appearance since a murder bid in Omagh earlier this year.
Mr Caldwell was seriously injured after he was shot several times at a sports centre in the Co Tyrone town in February after coaching a youth sports team.
The Queen spent some minutes speaking with Mr Caldwell during the garden party and he is understood to have had a private audience with the King earlier.
9. Royal garden party
King Charles meets some of the garden party guests. Photo: Kelvin Boyes /Press Eye
10. Royal garden party
King Charles pictured with DUP leader Sir Jeffrey Donaldson at the Hillsborough Castle garden party. Photo: Kelvin Boyes /Press Eye
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