Sarge, Ding-Dong and Carter try to resist a heavily pregnant Christmas allegory.
Psychoanalysis is a dangerous thing.
Our trio are reunited with their long-lost son.
The arrival of guest star Peter Vaughan starts talk of mutiny.
Carter and Ding-Ding compete over a chance at the fabled Heathrow job.
The Prodigal Swan returns.
The boys get new surveillance equipment and are soon under threat of being replaced.