"No smiling. Not even a wee Anne Robinson. The look we're going for should be solemn respect. Like blokes modelling underpants," scolds Malcom Tucker (Peter Capaldi) to his team in this fifth episode of Armando Iannucci's political comedy series, back after a one-week hiatus. Tonight, Nicola Murray (Rebecca Front) and Peter Mannion (Roger Allam) are both on the back foot after the unravelling of the key-worker housing sell-off policy.

Malcolm Tucker (Peter Capaldi) is back with us, storming around like an angry undertaker, plotting against lame-duck party leader Nicola Murray (Rebecca Front).

To orchestrate her downfall, he has deliberately put her on a train to Bradford while he sets off various PR bombs. But he needs Olly to help, and Olly is in hospital. Malcolm visits, with a bouquet, and Olly is touched. "Did you actually buy me flowers, Malcolm?" he splutters. "No, no," protests the lethal aide. "It's one of the many advantages of living near an accident blackspot."

The lavishly profane Malcolm-scenes are intercut with a frantic Nicola trying to salvage her political career from a train carriage, without the TV crew who are following her noticing. And Rebecca Front does panic brilliantly.

The excellent political satire continues with Malcolm Tucker (Peter Capaldi) ramping up his stealth campaign to oust the Leader of the Opposition, Nicola Murray (Rebecca Front). He packs Murray off to canvas at a party event in Bradford, leaving him free to move his political pawns into place. This means forcing policy advisor Ollie Reeder (Chris Addison) to coerce shadow ministers into joining the coup from a hospital bed, where he's recovering from an appendectomy.

Nervous Nicola Murray, now Leader of the Opposition, is practising her solemn walk for the Remembrance Day wreath laying ceremony. She's not very good at it, as her éminence grise Malcolm Tucker observes, "You're not throwing a straw frisbee in slow motion." Yes, mighty Malcolm (Peter Capaldi) is back, surfing a rip-tide of invective, and he's already plotting to bring down the hapless Murray (Rebecca Front) whose first major policy initiative, under the unfortunate heading of "Quiet Bat People", is torpedoed by everyone, particularly those closest to her.

Tucker is greyer than ever, like an ash-cloud of malevolence, which is an effective camouflage when he practises his dark arts in even darker cupboards, pulling would-be allies to one side for a little word. Of course, most of his words consist of four letters, so brace yourselves. Malcolm, you have been missed.

Life continues to veer from crisis to disaster in the fourth series of Armando Iannucci's sublime political comedy, with media strategist Malcolm Tucker (Peter Capaldi) here making his first appearance of the series. Leader of the Opposition Nicola Murray (Rebecca Front) struggles with left and right in more ways than one as she prepares for a public appearance with the PM and tries to manoeuvre away from the "assistance" of Tucker.

Rebecca Front interview

Rebecca Front talks about the new series of The Thick Of It, working with Peter Capaldi and why she enjoys ordering around Kevin Whately in Lewis.

Malcolm Tucker's 'swear-athon' broadcast in creche

Alistair Campbell and Peter Capaldi were left red-faced after their sponsored swear-athon was accidentally broadcast into a creche.

An equalities minister who has voted against racial and sexual equality rights. Chuckle. A health secretary who supports homeopathy. Ha! It's good, this politics malarkey, isn't it? A right giggle. Some might think it beyond parody. But thankfully not The Thick of It crew, who, three years after its last series, returned last night with an eagerly awaited fourth to take on the calamity coalition.

First, the good. In fact, the excellent. Roger Allam as the Tory MP Peter Mannion, new head of Dosac - the Department of Social Affairs and Citizenship - fills the role perfectly. The floppy hair, the floundering as he tried to explain a "networked nation" that was beyond him, the barely concealed contempt for those he works with ("I'm bored of this," he said, walking out of a meeting with his junior minister. "I'm going for a Twix") and those he works for. ("I hate schoolchildren. They don't even have the vote. Might as well talk to fucking geese.")

Then there's the spin doctor Stewart Pearson, a lighter touch than attack dog Malcolm Tucker, all herbal teas, brainstorming and, in the words of Mannion aide Phil Smith, provider of "seven years of ear piss".

That Tories and Lib Dems might not get on behind closed doors has been the subject of satire ever since this bastard child of Westminster was conceived in May 2010, but it was moved on here to good effect. It reveals the flaws in the central characters and allows for the best line of the night, uttered by Ben Willbond as Lib Dem No 2 Adam Kenyon. "Landmark day," he said as Mannion finally destroyed the launch of the Liberals' "silicon playgrounds". "We bring in an idea, you like it, you nick it, you put two bullets in the back of its head. Snuff politics: you've got to laugh." And you did, you really did.

Yet not everything was quite so sparkling. Punchlines were occasionally heavy-handed and the ranting felt sometimes forced. Consider Lib Dem junior minister Fergus Williams's tirade at punchbag press officer Terri Coverley: "Now you like musicals. Well this is 'Tonight' from West Side Story, and I'm going to bring the bloody house down, so you can't rain on my parade, Funny Girl." Too contrived. Maybe that was the point, but it made you pine for the eloquent misanthropy of Peter Capaldi's expletive-fuelled Tucker. Luckily, he's back in episode two...

It was brave of creator Armando Iannucci to start a new season of The Thick of It (Saturday, BBC Two) without his expletive-spewing spin-doctor Malcolm Tucker (Peter Capaldi). It was the equivalent of hoping that no one would notice if an episode of Fawlty Towers featured only Manuel, Sybil and Polly. But fear not, Tucker/Basil will appear in the second episode, as was made clear when the producers lost their nerve and included a "next week" trailer featuring him.

In this new series, the Tories, though never named as such, were the senior partners in a Coalition - and I don't know whether it was deliberate, but the Lib Dem characters were instantly forgettable.

Given that a neologism from The Thick of It was used by Ed Miliband to describe George Osborne's budget - "omnishambles" - Iannucci must feel that modern political life is copying his satirical art a little too assiduously. It might explain why his usual brio seemed to be lacking in the opening scenes.

Where were the effortless similes and casual insults? It even seemed to borrow a scene from the film Anchorman in which its dim news presenter tries to join in a conversation about love, but can't think of any examples so randomly names things he can see. I love carpet. I love lamp.

These proved to be teething troubles and it got into his stride when Roger Allam as Peter Mannion MP struggled through an excruciating and pitch perfect press launch for "Silicon Playgrounds", the Coalition's digital youth policy. After that the confidence seemed to return. My favourite line came when No 10's loquacious spin-doctor said: "What was that word I used this morning?" Mannion replied: "You used a lot of words this morning. It was like a ----ing Will Self lecture."

On balance the BBC probably picked the worst week to launch the new series of The Thick Of It. Because no matter how funny the opener was it could never have been as amusing as the fallout from David Cameron's Cabinet reshuffle.

Of course, you may question how anything in life could possibly be funnier than Peter Capaldi's potty-mouthed spin doctor Malcolm Tucker - and you'd be right. But Tucker wasn't in it. And neither was Rebecca Front's Nicola Murray, his most recent sparring partner.

Still, as a scene-setter for the new Coalition era it did manage some laugh-out-loud moments. And the return of Roger Allam's gloriously withering Minister Peter Mannion was most welcome.

Although, not as welcome as the trailer for next Saturday's episode. Because Tucker is back. Murray is back. And the hair of Chris Addison's oily Ollie is insipidly slicked back. Happy (expletive deleted) days, as Tucker might say.