Pedzisa mutsara unotevera: Pamitambo yeOlympic yeTokyo ya2020, Duncan akahwina sirivha mumakwikwi emamita mazana maviri akasununguka, achipedzisa 0.04 masekondi kumashure kwemukundi uye waaitamba naye, Tom Dean. Akatevera nendarama sechikamu che4 × 200m freestyle relay team naTom Dean, James Guy, naMatt Richards, vachirihwina muEuropean rekodhi yemaminitsi matanhatu nemasekondi makumi mashanu nemashanu nemashanu. Akatorawo sirivha mumakwikwi evarume emamita 200 ari ega, uye imwe mumakwikwi evarume emamita 200 ari ega.
4 × 100 metres medley relay naLuke Greenbank, Adam Peaty, naJames Guy, vachimuita mutambi wekutanga weBritish kuhwina menduru ina mumutambo mumwe chete zvichitungamira kunzi akasarudzwa kuti ave knighthood.