He began playing youth rugby for Southend, and continued his education in the sport at New Hall School, under the tutelage of Tom Taylor, before joining Saracens in 2016.
[1] Injury ruled him for much of the 2017–18 season, but following his recovery, he featured for the Saracens 7s side in various tournaments, which included success in the Premiership Rugby Sevens Series.
[3] Hallett graduated into the senior academy in 2019 and made his Premiership debut a year later, at the age of 20, as a substitute in a 40–17 victory over Exeter Chiefs.
[6] In his first competitive appearance as a full-time senior player in September 2022, he scored his first try, after coming off the bench during a 41–39 win against Gloucester.
[7] Hallett represented England at numerous age-group levels as a teenager, including U16s and U17s.