Earlier in her career, just after her graduation, she joined the Cambridge Experimental Theatre company and toured Europe for a year performing Shakespeare. She then founded the Snarling Beasties company and spent the next 15 years writing, directing and performing in plays they took around the world. In 2001, she adapted Dodie Smith’s The Hundred and One Dalmatians for the stage.[1]
Nativity!, Isitt's third feature film, starring Martin Freeman, was released in November 2009. It became the most successful British independent film of the year. The sequel, Nativity 2: Danger in the Manger, starred David Tennant. Released in November 2012, and was also a financial success, making twice the amount at the UK box office as the original. Two further sequels, Nativity 3: Dude, Where's My Donkey? and Nativity Rocks!, were released in 2014 and 2018 respectively. They were financial successes, but received mixed reviews from critics.[6]
In 2017, Isitt wrote, directed and composed the music for a stage musical based on the first film in the Nativity! with her partner Nicky Ager. Nativity! The Musical ran from 20th October until 6th January and starred Daniel Boys, Simon Lipkin and Sarah Earnshaw.[7] The show returned for a second tour in 2018.[8]Simon Lipkin returned in the lead role as Mr. Poppy, joined by Scott Garnham and Ashleigh Gray.[9] Garnham and Gray for a third tour in 2019, with Scott Paige playing the show's comic lead. However, Lipkin returned to reprise his role for the Hammersmith Apollo run of the show.[10] The musical ran at the Birmingham Rep for the 2022 Christmas season, after initially being postponed from 2020 and 2021 due to the COVID-19 pandemic.[11]
Isitt has a long-term partner, Nicky Ager, who works as the editor for her films as well as composing the music and writing the songs alongside Isitt. Together, they have a daughter, Sydney Isitt-Ager, who appeared in the first three Nativity films.[1][17][18]
Isitt was pregnant during filming for her first feature film - Nasty Neighbours - but she still completed the film, and took her then-two-month old to the Cannes Film Festival for the film's screening.[19]
Actors Robert Webb and Olivia Colman publicly criticised the film Confetti upon release.[24] The pair play a couple of naturists planning their wedding, and claim they were misled about the amount of nudity involved in the film.[25] Webb said in an interview that Isitt had told them their genitals would all be pixelated in the final film, and was not aware until the screening that this was not the case.[26][27] Colman and Webb started legal proceedings against the filmmaker, but these were eventually abandoned when the actors concluded it was too late and the lengthy process would prevent them from "pretending it didn't happen".[28]