Art imitates life imitates art. The Thick of It returns for a new – and final – series this week, but the line between Armando Iannucci's political satire and the real-life Westminster village is becoming increasingly blurred.

"Omnishambles", the word that defined George Osborne's U-turn riddled Budget, was coined by writer Tony Roche for the show's Olympic-standard swearer Malcolm Tucker.

The first episode of the new series, which airs on Saturday on BBC2, sees the junior partner of a coalition government struggling to cling to its big policy idea, Silicone Playgrounds, which has echoes of Michael Gove's plan for children to develop mobile phone apps. "Sometimes you will invent a story," Iannucci said recently, "and someone will say 'how did you find out about that?'" This seven-part series, charting a coalition in crisis and an Opposition in the doldrums, also features a Leveson-style inquiry, a battle for the leadership and U-turns on U-turns.

Old faces return – Nicola Murray MP is now in opposition and, more worryingly, party leader – while Peter Mannion is now the cabinet minister for the Department for Social Affairs and Citizenship.

But Tucker remains the star, tormenting everyone in his path, thanks to the handiwork of the show's "swearing consultant", Ian Martin. Iannucci is uneasy about Tucker's hero-status: "Malcolm is representative of all that is poisonous and has caused so much disrespect for politics and politicians in the past 15 or 20 years. I don't understand people like Alastair [Campbell] who worship him."

Amazingly it's the politicians he feels sorry for. "I think most politicians want to make a difference," he adds. "They have a set of principles, ideals or ambitions, and I suspect the bulk of them stay like that."

As MPs return to stumble along Westminster's corridors of power this week, Iannucci's creation will seem painfully close to home.

The Thick of It: HM Government

Peter Mannion:

Exasperated Secretary of State at the Department of Social Affairs and Citizenship (DoSAC), baffled by the 21st century and still coming to terms with sharing his office – and life – with his junior coalition partner.

Most like Ken Clarke

Stewart Pearson:

The blue-sky-thinking guru, once obsessed with not wearing ties, is now No 10's communications director, coping with Steve Jobs's death by drowning in jargon.

Most like Steve Hilton

Glenn Cullen:

After the election he couldn't face opposition so defected to become 'Fourth Sector Guru' to the junior coalition party, which he calls The Inbetweeners.

Most like Andrew Adonis

Fergus Williams:

Fully digital junior DoSAC minister gets in early only to see his policies pinched by his larger coalition partner.

Most like Danny Alexander

The Thick of It: HM Opposition

Malcolm Tucker:

Out of power, but still powerful, the potty-mouthed maniac is already plotting to oust Murray.

Most like Alastair Campbell

Dan Miller:

Efforlessly charming, but ruthlessly ambitious, he has not given up the idea of becoming party leader, even if it means having clandestine meetings in cupboards with Tucker.

Most like: David Miliband

Ben Swaine:

The blinky former minister who suffered a Newsnight car-crash interview, now in the Shadow Cabinet and willing to do Tucker's dirty work.

Most like Ed Balls

Nicola Murray:

A bizarre quirk of party rules has catapulted the luckless former DoSAC minister into the job of leader of the opposition. But she struggles with walking, talking, and being followed by an 8ft pork chop.