This was the sixth episode to be produced, but was the first one to air.
George Cowley fought as a volunteer for the Republicans in the Spanish Civil War. He was wounded in the leg during an air attack by German bombers, which is why he limped during season one. Presumably, he had surgery for the bullet to be removed by season two, as the limp disappeared. After Spain, Cowley served as a commando in World War II and the Korean War, eventually reaching the rank of Major before joining MI6, and then being appointed as head of MI5, before leaving to create CI5. According to Bodie and Doyle in Mixed Doubles (1980), Cowley appears to be religious. His old nickname in MI6 was "Morris" based on the contemporary car the Morris Cowley. CI5 Agents occasionally refer to him as "The Cow". His nickname for Bodie and Doyle is "The Bisto Kids" based on a pair of cartoon characters used to advertise gravy. His favorite drink is malt Scotch. In reality despite his martial bearing Gordon Jackson never served in the military, spending World War 2 building engines at the Rolls Royce factory in Glasgow.
The original title for this episode was "Timebomb".
George Cowley was born in Glasgow and attended university where he was renowned for his libertarian views, having his head split open at an anti-fascist rally. He served as a volunteer in the International Brigades during the Spanish Civil War, fighting on the Republican side. In the first season he limps as a result of a bullet wound sustained by being strafed by a German bomber but this disappears in season 2 so he presumably has surgery to correct it. He served as a commando in World War 2 and the Korean War rising to the rank of Major and afterwards joined MI6 before forming CI5 in the mid 1970s. He is religious, drinks malt scotch and was nicknamed 'Morris' in his youth after the contemporary car, the Morris Cowley. Bodie and Doyle refer to him as 'The Cow' and his nickname for them is 'The Bisto Kids' after a pair of cartoon characters used to advertise instant gravy.
The radio news bulletins make reference to 'the American President', yet do not name him. The President of the USA at the time the episode was made and first broadcast was Jimmy Carter, elected in 1976 and in office from 20 January 1977 to 20 January 1981.