Lorna Johnstone was born into a wealthy family, her grandfather founded an engineering company in Yorkshire and later became a member of parliament, and was brought up around horses as the family were strongly involved in foxhunting with the York and Ainsty Hunt. Thirteen times a national champion in dressage she would have been in consideration for a place at the Olympics at both London and Helsinki if women had been allowed to take part. Johnstone is the oldest female competitor ever at the Olympic Games, having turned 70 years old only three days before she competed in dressage at the 1972 Olympic Games. She is also the second oldest female competitor ever, having been 66 years old when she competed in 1968. Johnstone also competed in 1956, but was not the oldest female competitor in Stockholm, that being her dressage teammate Lilian Williams, who was 61 years old in 1956. She competed in dressage until past her eightieth birthday and was of the inaugural inductees of the Royal Horse Society Hall of Fame.