[2] He made his debut for Worcester Warriors at the age of 17 against London Scottish in the RFU Championship semi-finals; becoming the youngest player to feature in the play-offs.
[4] By the time he extended his contract with Worcester in December 2018 he was used predominantly at fly half.
[5] On 5 October 2022 all Worcester players had their contacts terminated due to the liquidation of the company to which they were contracted.
[8] On 26 January 2023, Leicester Tigers announced Shillcock as a new signing for the 2023-24 season.
[9] In February 2024 Shillcock scored nine points for the England A side during a victory over Portugal.