Doon Mackichan stars as the proprietor of a down-market hair salon in the promising new comedy Quick Cuts. It's not the most original idea in the world for a sitcom, but it is a robust one, with the turnover of customers giving you all kinds of opportunity for comic interludes that are a break from the ensemble dynamic ("Do you ever worry that you might be the anti-Christ," asked one pensive punter).

And it has a very good cast, including Lucinda Dryzek as Becks, the resident airhead and Jessica Gunning as a staff member trying to break a long sexual drought. It's described as semi-improvised in the Radio Times. I do hope that one of the improvised moments was when Mackichan sheared a clean swathe through the hair of her errant boyfriend, Trevor - a genuinely unexpected sight-gag. But if so, Paul Reynolds deserves some kind of medal for staying in character.

BBC1's new domestic sitcom Life of Riley has the bad luck to begin when the triumphant second series of Outnumbered is still fresh in our minds. By noticing the fairly obvious fact that family life is funny just the way it is, Outnumbered has demonstrated that the layers of sitcom contrivance in other shows are both tired and unnecessary, and actually smother the comedy.

Here, Caroline Quentin plays Maddy Riley, whose family consists of a nine-year-old child from her previous marriage, her new husband and his two teenagers, and a baby. Maggie last night found a pregnancy-testing kit - which, despite being unopened, instantly convinced her young Katie (Lucinda Dryzek) must be pregnant. Next, husband Jim (Neil Dudgeon) found the same kit and decided Maddy must be pregnant. And so on.

Needless to say, it's much easier to sneer at a determinedly mainstream sitcom than to write one. It's also true that Life of Riley does have some nice lines, especially when simply observing family life. The trouble last night was that with all that wildly implausible plotting to be done, there just wasn't room for enough of them. Instead, we ended up spending another half-hour firmly on Planet Sitcom: that strange world where people behave not like anybody in real life, but merely like people in other sitcoms.