Both the best and worst thing you can say about Secret Diary Of A Call Girl is that it’s exactly the kind of thing you’d expect to find screening on ITV2. Whether you think that’s a positive or a negative will dictate how you feel about the programme itself.

In its final series, Secret Diary remains a distinctly odd experience – a million miles away from the cynical blog entries that inspired it – and has become a fluffy, soft focus tale of a girl who makes her living as a hooker, but is living like you’d want your big sister to be. It’s certainly witty (occasionally) and it’s certainly sexy (occasionally), and is comfortably aimed at the female quotient of the audience (most of the men might be annoyed by the actual storylines that crop up in-between the more risqué scenes, and be a lot less embarrassed if their partners walked in to find them watching significantly more top shelf).

But the storyline… Such as it is. The story arc of Secret Diary has now not only caught up with the real life events that have inspired the episodes, but now taken them over into their own life. During this fourth year, Belle is courted by executives who want to make a movie based on her book (rather than an ITV series), leaving open discussions as to who could play Belle on screen, and presumably ignoring that there’s an actress in ‘real life’ called Billie Piper who looks pretty similar.

Now, close to a case of the pop starlet eating herself (not literally, before you go rooting around in the extras), this faces a similar challenge to a series like Sex And The City – not because of the obvious connection, but because it’s based on a book that had a very definite beginning, middle, and end – these characters are now having lives and storylines that were never intended. Inevitably, they become a little weaker, particularly as none of the characters are really allowed to develop and grow – hardly surprising, as the source material was simply commentary and opinion.

As sexy and as unthreatening as a slightly upper-class hen party (again, your instinctive reaction to that description will dictate as to whether that’s a good thing or not), this has the air of something that’s gone on longer than anybody expected – however, nobody seems to mind. With mutterings of a movie surfacing, it’s not time to leave your cash on the bedside just yet.

Released on DVD on Monday 4th April 2011 by Warner Home Video.

> Order the Series 4 DVD on Amazon.

Watch the Series 4 trailer…