IN a modern office building towering above Euston station, Stephen Mangan, Anthony Head and Sharon Horgan have been hard at work on a new Channel 4 comedy.

Free Agents is a slick new show from the team behind Spaced, about a dysfunctional couple of talent agents and their sex-mad boss.

The show started life as a pilot for Channel 4's 25th anniversary comedy showcase in 2007 and like all good comedies, was promptly commissioned for a full six-part series.

Alex (Stephen) is going through a messy divorce, but has fallen in love – and into bed – with Helen (Sharon), who's still grieving after the death of her fiance.

"All the basics you need for a cracking comedy," jokes Stephen, 36.

"It's nice not to play the most obnoxious person in a show for a change, you know Anthony's playing the character I would normally play," says Stephen, referring to his role in Green Wing as Guy Secretan.

"I like the dynamic between me and Sharon, the sort of 'will they won't they' and the fact they're two very damaged people who are working in this insane world of 'agenting' and they're handling their problems quite differently.

"He's a very sensitive character, who's always crying and he just really wants a bit of contact with someone else to help him through it. Whereas she's much more tough and she's pushing him away all the time but he's not easily deterred."

The first episode opens with the two in bed together, having a rather awkward post-coital conversation. It looks as though Helen might actually let Alex stay the night, until he starts crying about the children he never gets to see – but it's not "comedy crying", he says

"There is a certain element of drama to this as well and actually that's quite interesting for me because I'm not playing a funny part in that way."

Besides the Creative Management Associates (CMA) headquarters in Euston, most of the show was shot in and around Soho on 35m film, giving it a kind of Sex And The City-style look and feel.

"This show breaks new ground," says Stephen. "I don't know a show like it.

"It has adult themes done with poignancy and comedy and I suppose American shows like Sex And The City do that very well, they deal with heart-breaking and very adult themes but with a bit of style and comedy, so I hope we pull that off."

We see Alex and Helen walking through places like Berwick Street market on their way to screenings and client meetings, scenes that were fun but also hair-raising to film.

"The West End attracts its fair share of nutters as well and you get people walking in with their cameras in the middle of the shot just taking a picture."

Free Agents was written by Chris Neil and based on his experiences as a showbiz agent for the likes of Robert Carlyle, Matt Lucas and David Walliams.

"I just followed him around and looked at him a lot," Stephen quips.

Although there aren't any celebrity cameos in the first series, Stephen says the potential is there but it's more about the three main characters.

Then there's the incredibly fruity and graphic language that comes from the mouth of Alex's boss Stephen (Anthony).

"He's hilarious, because he's so appallingly, grimly obscene but Anthony plays him in such a charming way that you kind of forgive him for all the absolutely disgusting stuff that comes out."