Ruth Wilson plays her own grandmother, Alison Wilson. Based on real-life events, the series follows Alison Wilson who discovers secrets about her husband Alexander 'Alec' Wilson after he dies unexpectedly in 1963. Alison and Alec's younger son, Nigel, is Ruth's father.
MI6 is Britain's foreign intelligence service, while MI5 is Britain's domestic intelligence service.
Ruth Wilson's characters in The Affair and in Freezing are also called Alison.
Iain Glen and Ian McElhinney acted together in the HBO series Game of Thrones (2009), sharing many scenes together.