Royal correspondent James Whitaker said: “It happened in front of the whole family at the Queen’s country residence in Scotland.
"She was late into breakfast and everybody had got a copy of the Daily Mirror.
"As she walked into the room, they all stuffed it under their Times and Telegraphs and that sort of thing.
"She knew the game was up the second she walked into the room.
Andrew and Fergie publicly announced their separation one month after the photographs were printed.
Despite divorcing in 1996, the pair have maintained a close friendship.