Baader-Meinhof gang, or the Red Army Faction, was founded by Andreas Baader and Ulrike Meinhof. It was a left-wing (promoting social equality, nationalizing the private sector) West German radical terrorist organization, linked to a number of kidnappings and bombings throughout the country.
Simona Brown, who played Rachel, was also in another John le Carré mini-series, The Night Manager (2016).
The first episode registered 6.81 million UK viewers.