Born in Peckham,[1] Lansiquot first ran inside 12 seconds for the 100 metres as a 15-year-old, winning the Surrey Schools Championships in 11.98 in June 2013 and winning the English Schools Championships in 11.91 in July 2013.[2]
Lansiquot ran 11.56 secs in her heat at the 2015 European Junior Championships, before going on to finish fifth in the final in 11.74.[3] She then won a gold medal in the 4 × 100 metres relay. The following year, she ran 11.17 secs in her heat at the 2016 World U20 Championships, to move to second on the UK under 20 all-time list behind Dina Asher-Smith (11.14 in 2014). She finished fourth in the final with 11.37 secs. She also finished fourth in the 100 metres final at the 2017 European U23 Championships in 11.58.
At the 2018 Anniversary Games in London, Lansiquot ran a season's best of 11.19 secs in her heat, before improving her personal best to 11.11 in the final, to move to sixth on the UK all-time list. She ranks eighth on the UK all-time 60 metres list with 7.21 secs (2018).
In August 2018 at the European Championships in Berlin, Lansiquot finished sixth in the 100 metres final in 11.14 secs, before winning a gold medal in the 4 × 100 metres relay.[4]
At the 2019 World Championships in Doha, she reached the 100 metres semi-finals and ran 11.35 secs, having run 11.31 to qualify as a fastest loser from the preliminary round.[5] She went on to win a silver medal in the 4 × 100m relay, where she ran in the heats before having to withdraw from the final due to injury.
In 2023, she improved her 100m personal best to 10.99 seconds,[7] becoming the third British woman ever to go under 11 seconds. She was selected for the World Championships in the 100 m, however she was disqualified for a false start. She won a bronze medal in the 4x100m relay, where she ran on the second leg. [8][9]
Lansiquot studied psychology at King's College London.[13] She is of Saint Lucian descent through her father. She is named after the Trinidadian cricketer Brian Lara.[14]
She is currently dating West End actor Dom Simpson, who currently stars as Christian in Moulin Rouge The Musical.