Suffice to say Mark (Robert Bathurst) accidentally featured in the home-made blue video starring his wife and her lover. How? Watch it and see.
Webmaster's comment: This issue of the Radio Times incorrectly states that Joking Apart won a Bafta. This is the earliest instance I can find of this frequently repeated mistake. The series won an award at the Montreux Festival, not a Bafta; it was Steven Moffat's other series, Press Gang, that won a Bafta.