Whether it's vanity or irony, the business of television has long been a popular subject matter for TV shows. From The Mary Tyler Moore Show in the 1970s through to Murphy Brown, The Newsroom, Sports Night and Drop the Dead Donkey, it seems the old adage 'write what you know' is widely followed. But while news and sports shows have been thoroughly satirised and lampooned, TV comedy had escaped largely unscathed - until recently. Following on from Ricky Gervais' superb Extras and former Friend Lisa Kudrow's underrated The Comeback, which both sent up sitcoms (and television in general), two new shows are taking on the world of live comedy. First up, 30 Rock (Star World, Thursdays at 9pm) is an irreverent sitcom from former Saturday Night Live writer/actress Tina Fey that is set, funnily enough, around a Saturday Night Live-esque production, The Girlie Show. Fey plays Liz Lemon, the show's neurotic head writer, who finds comedy can be a serious business when new head of programming Jack Donaghy (Alec Baldwin, in a Golden Globe-winning role) arrives and starts making wholesale changes to her show. 'Sometimes you have to change things that are perfectly good to make them your own,' he tells Lemon when she protests that the show is fine as it is. Her displeasure is compounded by the fact Donaghy made his name marketing microwave ovens and knows almost nothing about TV. Among his corporate-jargon-wrapped ideas, which aim to bring 'the third kind of heat' to the show in order to 'hit key demographics and effectively synergise backward overflow', is the suggestion she hire unstable mainstream comedian Tracy Jordan (Tracy Morgan, Saturday Night Live). Fey is great as the frustrated Lemon, continually caught between artistic integrity and corporate interference, while Morgan gives a madcap performance as Jordan, an amalgamation of lowest-common-denominator comics such as Martin Lawrence and the Wayans brothers (Jordan's fictional film credits include Black Cop, White Cop and Who Dat Ninja?). The supporting cast features known comic talents such as Jane Krakowski (Ally McBeal) and Jack McBrayer (Talladega Nights) but it's Baldwin who steals the show. Far from being a two-dimensional overbearing boss, he gives a superbly idiosyncratic performance as Donaghy, alternating classic put-downs (to Fey: 'I like you. You have the boldness of a much younger woman') with almost childlike pouting when his ideas are not embraced. Wonderfully written and filled with sly digs at the entertainment industry, this is another great American comedy in what is fast becoming a veritable movement. Also delving behind the scenes of a fictional live sketch-comedy show is Studio 60 on the Sunset Strip (TVB Pearl, Thursdays at midnight), which started last week. Rather than playing it for laughs, however, Studio 60 takes the drama route, and features another former Friend, Matthew Perry, who plays head writer Matt Albie. As smart and insightful as you would expect from a show created by Aaron Sorkin (The West Wing, Sports Night), Studio 60 lays bare the hypocrisies of American TV and illustrates the nigh impossibility of being cutting edge when prime-time slots demand the widest possible appeal with the least possible controversy. Unfortunately, such intelligent themes have not translated into high audience ratings in the US. Maybe they should have thrown in a few fart jokes. Oscar-winner Helen Mirren (right) makes a welcome, albeit brief, return to the small screen this week in Prime Suspect (ATV World, today at 9pm). This British crime drama, in which Mirren stars as Detective Chief Inspector Jane Tennison - arguably her most famous role - began in 1991. A two story, four-episode run that brings the show to its conclusion begins with tonight's instalment, The Last Witness Pt1, which sees Tennison investigating a sadistic murder that may have links to former Balkan war criminals. The harrowing case concludes next week, after which the second two-parter, The Final Act, brings the curtain down on Prime Suspect. Chronicling the difficulties and prejudices faced by an iron-willed woman in a male-dominated environment, Prime Suspect has become the standard by which other British crime dramas must be judged, and The Last Witness represents what is probably the series' apex. Mirren has never been better as the stubborn and world-weary Tennison while the plot is so expertly wrought and the denouement so ingenious, it makes most of its peers look like Police Academy. The Final Act can't quite keep up this high standard, yet it manages to give the series and the character of Tennison the send-off they deserve. Prime television.