Factual error: At the end the Chief Constable tells Jo she is being transferred to CID. She then says that most people would be happy to be told they'd been promoted to sergeant. But she hasn't been told she's been promoted to sergeant, since officers are transferred to CID in their current rank (detective constable in her case) and one isn't just promoted to sergeant; it requires passing a national-level exam and an interview. Chief constables can't just arbitrarily promote a constable to sergeant. Jo then salutes, something that hasn't been done by the British police for decades.