Darren Boyd & Rebekah Staton: Spy's talented comedy duo

As the MI5 comedy ends its series with a Christmas special, we meet the stars behind the show's screen romance.

The stringently funny comedy ends its second series with an episode that, in proper Christmas-special tradition, is twice the usual length and 40 per cent sillier. Ten-year-old Marcus (the freakishly good Jude Wright) auditions fellow pupils for a seasonal musical, with customary ruthlessness: "There are prisoners in Guantánamo being waterboarded who sound better than you..." Even his dad Tim fails to win a part, despite Darren Boyd unleashing a stunning singing voice.

When MI5 agent Tim's office affair with Caitlin (Rebekah Staton) is discovered, there are guns drawn and truths told. Back at school, a talent shortage on the big night means desperate time-filling, à la gourmet night at Fawlty Towers.

From pantomime, we leapt to silent film for the last of Sky's quiet but acclaimed Little Crackers. Now in its third series, it too benefits from the indulgence of its creators, each episode giving a funny person the chance to make a 10-minute film inspired by their own lives. It's a bit like asking a Desert Island Discs subject to turn their best anecdote into a comedy short.

Darren Boyd, seen last year in the BBC's acclaimed Holy Flying Circus, admitted in the making-of film after his directorial debut that it was only very loosely inspired by real events, and stood more as a love letter of sorts to his mum (he wouldn't say how) as well as silent movies.

He played his own dad, sort of, alongside Doon Mackichan as his mum, sort of, as parents whose obsession with ballroom dancing left little room for their son. The absence of words demanded all the muscles of Mackichan's expressive face, most notably in a scene in which she gamely squished her face into the glass of a trophy cabinet in a grotesque staring contest with a rival dancer. Her eyes said more than those of even the greatest pantomime dame. Oh yes they did (sorry).

The seasonal series of autobiographical shorts goes out with a bang as two final celebs put dramatic flesh on the bones of a youthful memory. For actress Sharon Horgan, that means stepping into her mum's shoes for a spot of Christmas turkey plucking, while for Spy regular Darren Boyd, it takes the form of an emotionally scarring experience when a lad's moment in the spotlight at the school's Christmas concert clashes with his parents' social life.

A Bafta winner and nominated for (but didn't win) an International Emmy last month, this espionage comedy caper certainly has its admirers even if some may find it overly silly. That said, the cast cannot be faulted, chief among them are the excellent Darren Boyd as the hapless, accidental spy Tim, and Robert Lindsay as his maniac boss, "The Examiner". In tonight's episode Tim gets just the required push needed to try to rekindle his romance with fellow spook Caitlin (Rebekah Staton) after he discovers he's on an assassin's hit list. Meanwhile, the precocious Marcus (the often scene-stealing Jude Wright), finds the perfect moment to humiliate a rival at school as he again seeks the affections of Justine (Ellie Hopkins).

Tonight's double header of autobiographical tales features Sharon Horgan and Darren Boyd. First, Horgan's story recalls Christmas 1984 on the family turkey farm. Young Sharon (Katherine Rose Morley) isn't looking forward to her time plucking turkeys until fellow plucker James (Sam Keeley) turns up. They flirt and arrange a date, but he fails to show, leading to a series of disasters for the Horgan family. At 9.30pm, Darren Boyd's tale tells of when he was chosen to sing at his school's Christmas concert.

Darren Boyd interview

TV Choice asked Darren Boyd to blow a few official secrets about the Spy Christmas special...

Nope, they still haven't done a weak episode. This week, insane MI5 chief the Examiner (Robert Lindsay) has made an unbroadcastable recruitment video, so Tim and Caitlin step in. But they can't act until they assume ludicrous, sexed-up B-movie personas.

The role-playing reignites the spark between them and takes Tim out of his normal, footling self. He sticks with the stubble, blond wig and leather jacket even after filming. He's a new man, and Darren Boyd is a new variety of hilarious.

Meanwhile, Marcus is on a father-and-son TV quiz. Naturally, he's got a ringer in to replace his embarrassing dad, but the laws of sitcom say the two storylines must meet.

Spy has invested in a top-notch ensemble, but the star is still Bafta-winner Darren Boyd as rubbish spy Tim. All Boyd's strengths are in evidence this week: rising irritation as Tim tries to give a talk at his son Marcus's school; pratfalling as he tries to conceal that he's taken Marcus with him to the office, which isn't really feasible at MI5; and a glimmer of lovable warmth and vulnerability as the fiasco brings father and child closer.

Meanwhile, suddenly putting a character on drugs might normally be an unacceptable short cut, but when it's Robert Lindsay, trouserless and rattling with amphetamines, it's more than forgivable. He keeps thinking he's seen a demonic boy in the corridor, which of course he has.