The title comes from The Scarlet Pimpernel by Baroness Emmuska Orczy: "They seek him here, they seek him there. Those Frenchies seek him everywhere. Is he in heaven or is he in hell? That demmed elusive Pimpernel."
Raymond Clandillon arrives in a 1952 Daimler Consort.
Matthew Marsh plays Jack Braxton in this episode. He previously played the role of Tony Carter in episode 6.3, Painted in Blood (2003).
Richard Hope plays Neville Hayward in this episode. He previously played the role of Gordon Brierly in episode 3.3, Judgement Day (2000).
Marian McLoughlin plays Gwen Morrison in this episode. She previously played the role of Barbara Judd in episode 4.5, Dark Autumn (2001).