Bowler - hat inspection for Household Cavalry. Mounted troopers of the Household Cavalry in glittering breast - plates and helmets were under inspection by men in civilian suits. They were being pre - judged at the Household Cavalry parade Ground , Hyde Park , London , for the Princess Elizabeth Challenge Cup competition at next week ' s Richmond Royal Horse Show . Photo Shows ; A Trooper of the Royal Horse Guards and his mount being closely examined by bowler - hatted judges . 6 June 1952