A large nail bomb hidden in a car parked on South Carriage Drive exploded as the Queen's Life Guard passed. It was set by the IRA and probably controlled remotely. Four members of The Blues and Royals lost their lives. Twelve soldiers and six civilians were injured. Seven horses died. A seriously injured horse, Sefton, survived and became well-known, being awarded "Horse of the Year". The soldiers and horses were from Hyde Park Barracks.
Two hours later a bomb in Regent's Park exploded.
2018: Andrew Parker Bowles revealed that the Queen referred to this day as “the most ghastly day of my life”.