The Simon & Garfunkel lookalikes (played by Paul Casar and Simon Farnaby) are listed in the credits as characters Paul and Art. When the policeman asks for their names during the stakeout bust they give them as Paul Lee and Philip Peters. Peters & Lee were a British folk duo (Lennie Peters, Dianne Lee) who had hits in the 1970s and 80s.
The characters known as Simon & Garfunkel are actually called Peters (Paul Casar) & Lee (Simon Farnaby) in the series.
Toby Jones (Lance), Mackenzie Crook (Andy) and Simon Farnaby (Art) also appeared in Christopher Robin (2018) together as Owl, Newspaper seller & Taxi driver respectively.