Katarina Mary Johnson-Thompson is a British heptathlete. Britain's Katarina Johnson-Thompson, who has long threatened to break through into the golden ranks of the world's top all-round athletes,. At the age of 19, KJT - as she was starting to be affectionately known - had finished a very creditable 13th. Katarina Johnson-Thompson - world heptathlon champion and ambassador of our new funetics programme for primary school age children. Contact Team KJT At the tender age of 26, the two-time Olympian has an impressive athletics resume which includes her most recent victory in Doha, Qatar, which saw her crowned as the World Champion Heptathlete.