Bells (Blackadder) marks the first appearance of the Bob/Kate and Flashheart archetypes that appear again in "Blackadder Goes Forth". Rik Mayall, who played Lord Flashheart, allegedly designed the character's costume himself. John Lloyd has said that Mayall virtually rewrote his part to feature "loads of jokes", which annoyed the writers, Curtis and Elton. It was the only episode of the series to feature location filming, at Wilton House in Wiltshire. The music performed as Blackadder courts "Bob" is Vaughan Williams' "Fantasia on Greensleeves". In 1993, in conjunction with Comic Relief, this episode was given away free on cassette tape with boxes of
Spooks (series 3) and guest appearances. Megan Dodds returns as CIA liaison Christine Dale in the first episode. Tim McInnerny recurs as JIC chairman Oliver Mace. McInnerny was better known as a comedic actor, particularly for his role in "Blackadder", but the producers felt that quality made Mace a more menacing character. Richard Harrington plays Will North, Zoe's boyfriend turned fiancé. Ian McDiarmid guest stars as Fred Roberts. The producers noted that McDiarmid played Roberts with the right amount of vulnerability, strength and stubbornness. Indian actor Anupam Kher appears as Harakat in "Who Guards the Guards?". Oyelowo stated that Kher had an "instant