In 2003, he was honoured to be asked to portray his lifelong hero, Victorian engineer Isambard Kingdom Brunel in the BBC's "Seven Wonders of the Industrial World". In 2008, he played Mr Chivery in the TV serial "Little Dorrit", based on the novel by Charles Dickens. He has also appeared in the children's TV series "Summerhill", as an inspector. He played the role of an orthodox Jewish rabbi (Noach Marowski) in a 2008 edition of "Silent Witness". He played the role of Hermann van Daan in the 2009 BBC drama, The Diary of Anne Frank, as well as the part of David Cockram in the ITV drama Whatever It Takes, aired in the same year. In late 2012 Cook played the role of Peter in the ITV series "Mrs Biggs", a retired train driver, Ronnie Biggs befriends, employed by the gang to drive the hijacked train away during the Great Train Robbery. Cook played the company accountant, Mr Arthur Crabb, in the ITV series "Mr Selfridge" (2013 to 2016). In 2018 he portrayed a police chief in the BBC drama "The City And The City". In 2019 he played television producer Bill Calder in "Death in Paradise" S8:E3, and later portrayed Borch Three Jackdaws in Netflix's "The Witcher". In 2020 he played Stan Sturgess in the three-part fact-based BBC drama "The Salisbury Poisonings," which portrays the 2018 Novichok poisoning crisis in Salisbury, England. Cook played the father of Dawn Sturgess who was the only fatality in the crisis.