Jonathan Creek used to be an outsider. An enigma wrapped in a duffel coat wrapped in a windmill.

Everything about him was an act of non-conformation against the sweaty ‘90s urgency to be cool, and that in itself was cool. But on screen it was always the world around Creek that was painted as even stranger than he; ever so slightly deranged, bordering on the unreal. Jonathan, for all his eccentricities, was always the sanest voice in the locked room.

Now in the Twenty-Tweens he’s shed the gimmicks and become a mainstream man. He has a normal job, wears a normal suit, has an abnormally attractive wife, but it’s a normal marriage. His house is rambling, but it’s normal compared to one that’s cylindrical and can produce corn when the wind blows, and rambles nowhere near as much as David Renwick’s script.

Creek is no longer an outsider. Living in the kind of rural idyll that only exists in the heads of the Tory electorate and Enid Blyton, he’s barely a crime solver. He’s cosy. Fatted. Content.

Alan Davies has nothing to work with, reducing him to a bemused expression. And as Creek has normalised, the world around him has had to become increasingly abnormal, and less relatable to us, in order to keep feeding him puzzles.

All of which is really the only way you can explain what’s going on in ‘The Sinner and The Sandman’, which was less a mystery and more a thin collection of parish magazine brainteasers; too caught up in village gossip and unrealistic characterisation to remember that we tune in to Jonathan Creek for the mystery, not the jokes, even if you do have a good masturbatory euphemism or two.

The beginning, with Jonathan accidentally aiding two burglars, had about it the dark kind of fun that you’d have expected in the first few series, but from then on it swiftly became unbearably twee, with 20 minutes of mystery-free ambling that made Trumpton look like a hotbed of intrigue. And when mysteries did begin to surface they had all the fanfare of an announcement on a village hall noticeboard.

The explanation of how a predictive set of lottery numbers written decades ago by The Amazing Astrodamus and covered over by wallpaper could come true was a mixture of threadbare plausibility and unlikely coincidence; a credulity jump too cavernous even for this show. The ‘hunchback beast’ was obvious. The Sandman of the title felt shoehorned in.

But worst of all, everything just felt so lightweight, so parochial. With a lot of rambling set-up for very little payoff, this is the first ever Jonathan Creek to feel less like a dramatic illusion and more like a dinner party anecdote. ‘Good Lord! And he was in the bushes, recording everything all along? Heavens! Oh, pass the Stilton would you?’

The biggest mystery is one the show leaves us to answer: is there still a place for Jonathan Creek, or should we just leave the once outsider to his final trick – vanishing into everyday obscurity?

Aired at 9pm on Friday 7 March 2014 on BBC One.

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