expanding to cover extra wards, including a gynaecology ward, an acute assessment unit and a maternity ward. When the maternity ward and a special care baby unit were introduced during series four, Young explained that new wards were necessary to allow the crew to rotate sets, maximising filming potential. Episodes of Holby City cost around £370,000 to produce—more than the BBC soap opera EastEnders, at £130,000 per episode, but less than Casualty at £450,000 per episode, or Dalziel and Pascoe at £700–800,000 per episode. As Holby City is a high-volume, year-round production, it has relatively low production costs. Set-up costs can be spread over many years and standing sets can be repeatedly re-used, which is not the case for shorter series or one-off dramas. Young remained an executive producer of Holby City until 2004, when he left the BBC to work for production company 19 TV. Former Casualty producer Johnathan Young was an executive producer for the duration of Holby first series, before joining Channel 4 in 1999. Kathleen Hutchison served alongside Mal Young as co-executive producer from 2003 to 2004, when she left the series to become executive producer of EastEnders. Hutchison was succeeded by former series producer Stokes, who remained working on Holby City until 2006, when McHale returned to the series. He resigned from the position in 2009, and was succeeded by Belinda Campbell in 2010. In February 2011, it was announced that Johnathan Young would return to the BBC from March, succeeding Campbell as executive producer of both Casualty and Holby City. Two years later, the BBC advertised for a new executive producer for both shows. Oliver Kent was then announced as Young's successor, being promoted from senior producer at Holby City and series producer at Casualty. Kent was promoted to Head of Continuing Drama Series for BBC Studios in December 2016, and series producer Simon Harper was appointed the serial's acting executive producer. In June 2017, it was announced that Harper would take the job on a permanent basis. Kate Oates was hired as the show's senior executive producer in October 2018, working alongside Harper. She was promoted, succeeding Kent in his position, in April 2019. Harper remained in the role of executive producer until 2021. Writing Holby City storylines are planned eight months in advance. The series utilises a number of scriptwriters, who are found and scheduled by script development editor Simon Harper. Harper