- "Are we going to have to come over the river and potty-train you people?"
- ―Jools Siviter
|First seen||Traitor's Gate|
|Last seen||The Rose Bed Memoirs|
|Job||Section Head, MI6|
|Status||Working for MI5|
Siviter generally conforms to the stereotype of a condescending upper class English patrician, who barely bothers to disguise his contempt for those he perceives to be of lower class, inferior intellect or membership in what he calls the 'little sister' organisation, MI5.
Despite insisting that MI5 rigidly observe the delineation of responsibility that stipulates MI6 has control over all operations outside the UK, he has no compunction about breaking it himself and running assets inside the UK, including running surveillance on MI5 agents and framing a cabinet minister.
His exact position in MI6 is unclear, but the fact that he deals with Harry Pearce as an ostensible equal implies that he is a Section Head. He has alluded to serving in Russia and France in the past.
Siviter is a fan of opera, specifically Wagner. He states that he enjoys 'buggering skinheads', indicating that he may be homosexual, but it is possible that this was simply an attempt to shock a woman annoyed at him for texting in a theatre.
Siviter did not appear in the show after the first series probably due to portrayer Hugh Laurie's relocation to the USA in order to appear in the medical drama, House. He is however mentioned as a senior MI6 operative in a historical operation in Paris at the time of the death of Princess Diana. This information was used by Zafar Younis as part of the fictional story of how the Security Services could have assassinated the Princess in the series four finale..