In the final scene Jackson Lamb places a note on the columbarium. It reads "Dickie Bow served behind the wall - A Joe." The name "Dickie Bow" refers to an alternate name and spelling for Richard Bough, the retired agent killed in episode 1 of the second season. The wall refers to the Berlin Wall and the Iron Curtain during the Cold War - "behind" which Dickie served the MI5 in the Eastern Block.