This is the final episode of the series.
Jane's house is shown for the first time.
The BBC was interested in continuing the show for a fifth season, but cast availability was a problem. Writer Steven Moffat had become the showrunners for Doctor Who (2005). In actual fact, Coupling concluded in 2004, and the revived Doctor Who (2005) series would not even air its first episode until 2005, almost a year later; also, Coupling creator Moffat would not become the showrunner on Doctor Who (2005) until 2010. Therefore, Doctor Who (2005) had no bearing whatsoever on there being no Coupling fifth season.
Patrick Maitland's apartment number is revealed to appropriately be: 69.
The idea that Coupling (2000) ended because Steven Moffat had become the showrunner for Doctor Who (2005) does not hold up to scrutiny; Coupling (2000) concluded in 2004, and the revived Doctor Who (2005) series would not even air its first episode until 2005, almost a year later; also, Coupling (2000) creator Moffat would not become the showrunner on Doctor Who (2005) until 2010. Therefore, Doctor Who (2005) could have had no bearing whatsoever on there being no Coupling (2000) fifth season.