[6] On 22 May 2021, Harrington refereed the 2021 FA Trophy Final at Wembley Stadium.
Only eight days later, Harrington was back at Wembley when he officiated the 2021 EFL League One play-off final between Blackpool and Lincoln City.
[7] After becoming a Select Group 1 referee in June 2021, Harrington officiated his first Premier League game on 16 December 2021.
[8] Harrington attended Manor Community Academy for secondary school and English Martyrs School and Sixth Form College for sixth form.
[11] Prior to becoming a full-time referee, Harrington worked as a PE teacher at North Shore Academy.