The twenty-sixth series of the British medical drama television series Casualty commenced airing in the United Kingdom on BBC One on 13 August 2011, one week after the end of the previous series. It is the first series in the history of the show to begin without a break from the previous series and the first to begin in August rather than the traditional September launch. This series featured forty-two episodes, which was five episodes less than the previous series. Series twenty-six was the first series to broadcast in high definition, with the first high definition episode broadcast from episode 17. The episode also saw the first episode to be filmed at the new set in Cardiff. The show saw its twenty-fifth anniversary in September 2011 and in March 2012, the show aired their first ever t