It’s another complete U-turn of tone this week in Diddle Diddle Dumpling, starring Reece Shearsmith and Keeley Hawes as ordinary suburban couple David and Louise. Except, of course, there is nothing ordinary in Diddle Diddle Dumpling.

The premise is fiendishly simple. David is out jogging one day when he finds a shoe. Most people would leave it on a wall in the hope that the owner would return to claim it, but not David. And definitely not in an episode of Inside No 9. 

Instead he becomes obsessed with this piece of footwear. Naturally the shoe is a size nine. At one point I thought this episode was inspired by those stories of men who marry their VW Golfs or women who fancy the Eiffel Tower. But this goes off in a completely different direction as Louise tries to help David through this difficult period and keep the family together.

Despite the Good Life-style pristine suburban setting there is very little humour here. David and Louise’s house is nice but strangely sterile, with items often arranged symmetrically and side by side.  

Steve Pemberton pitches in as a friend who may be able to offer unemployed David some work, while Mathew Baynton has a cameo too (and Danny Baker's unmistakable voice pops up as a radio DJ). As I said, this is terrific instalment, but very low on laughs - even the nastiest episodes have often had humour cutting through them like a razor blade through skin.

So I’ll leave you with one of the first jokes I can ever remember seeing delivered on television. It might have been told originally by Bob Monkhouse or Leslie Crowther in the late sixties or early seventies. Someone who was very slick anyway. Here it is: A hippie gets on a train wearing only one shoe. A city gent sitting opposite him is concerned and asks “Did you lose a shoe?” "No, man,” the hippie replies. “I found one.”