Following on from a successful pilot in late 2010, BBC Four's commissioned a full series of this comedy drama loosely based on the novels by Douglas Adams, and starring Stephen Mangan as the holistic detective.

The first episode in the series, which sees Dirk deal with a murder that has links to the Pentagon, contains some funny situations created by Howard Overman, the man behind the adaptation. Such things include Dirk breaking into a house of the murder victim by smashing a glass door being witnessed by those inside. Then there's Dirk surveillance operation which goes completely wrong thanks to his partner/assistant MacDuff's (Darren Boyd) new chair.

However, personally speaking I'm one of those people who would have been happier with the original stories being adapted for the screen rather than having new ones developed. While it does contain some elements from the original books, such as Zen navigation (instead of using a map to go where you want to go, you follow someone who looks like they know where they go, often leading you to somewhere you need to be), it would be nice to see Adams's original tales on screen.

Still, if you too are annoyed by the lack of faithfulness in this adaptation, there are always the more faithful Radio 4 stories starring Harry Enfield, which does follow Adam's work much more closely (Electric Monks and Norse Gods included).

In Stephen Mangan's own words, Dirk Gently is "charming, ­irritating, bright, funny, hapless, unreadable, transparent, roguish, chaotic, philanthropic and possibly dishonest".

That's a lot of character traits to be dealing with, but we discover yet another, equally surprising side of his personality tonight as he shares fish and chips with a new female friend.

Dirk and MacDuff (Darren Boyd) are at Dirk's old college at Cambridge to take up the post of head of security.

His former teacher, Professor Jericho (Bill Paterson), is trying to develop artificial ­intelligence and he's afraid that someone is attempting to steal his research.

However, Dirk's more concerned with breaking into the college records to find out why he was expelled as a student.

It's just a shame creator Douglas Adams isn't around to see how Howard Overman has ­transferred Dirk to the screen.

He'd definitely approve.

The main plus point for Dirk Gently is having the consistently great Stephen Mangan on board in the lead role - he's certainly one of our most watchable comedy actors, and is in particularly fine form as the infuriatingly self-sure (but still rather lovely) private detective who believes in 'the fundamental interconnectedness of all things'.

Since the superb Sky One comedy Spy, my eyes have also been belatedly opened to the huge talent of Darren Boyd, who plays Gently's rather more conventional assistant-slash-business-partner MacDuff - so all in all I can't help but come to Dirk Gently with a whole heap of goodwill.

But I think my enjoyment of this episode can be put down to more than that. It's a great-looking thing, and the script was sharper than the pilot - I particularly enjoyed the line "his cheque bounced like the proverbial basketball... on a trampoline." Miss out the word "proverbial" there and it's prosaic; with it, it's a winner. There were little gems like this throughout the hour, and Douglas Adams's genius sense of the absurd is perfectly encapsulated in the idea of 'zen navigation': find a car that looks like it knows where it's going, and follow it. Pretty silly, but highly entertaining.

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I struggled with Dirk Gently (Monday, BBC Four). It had nothing to do with Stephen Mangan's considerable comedic talents, still less with Darren Boyd who plays Macduff, the Dr Watson to Dirk's Holmes. It is more to do with my devotion to Douglas Adams, upon whose comic novel this series is based. Adams was never well served by TV or film adaptations of his work, even big budget ones such as the 2005 film of The Hitchhiker's Guide to the Galaxy. His books always worked much better as radio adaptations that could leave the listener's imagination to fill in the gaps (indeed the Radio 4 version of Hitchhiker's even managed to be better than the book).

Jeeves and Wooster was similarly hard to make work on screen. Though Fry and Laurie's version was as good as any TV adaptation could be, it tried to tell the story through dialogue alone, which merely drew attention to the silliness of the plots. In PG Wodehouse, as in Douglas Adams, 90 per cent of the pleasure is in the prose, the narration, the felicities of language.

Over the course of a novel, Adams could afford to be quite subtle about Dirk's big idea, that all things are fundamentally interconnected. A TV adaptation can't be, and, as it keeps labouring the point, you find yourself saying: "Yes, yes, I get it." Perhaps as the series develops they will tone down this side of things.

Finally, and this is an anoraky point, Mangan looks nothing like the Dirk of the novels. At Cambridge Dirk was "rounder than the average undergraduate and wore more hats", and in later life he becomes rounder still, and scruffier, and more chaotic. Mangan seems too neat, too thin, too orderly.

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