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.