Sunday night is cosy drama night. It’s the law. People forget they have to return to work the next day by absorbing hours of fluff that any other night of the week would be judged as shallow and overly whimsical. Nostalgic/period dramas nestle in the schedules here, along with anything that features bucolic countryside. In some cases, like the former behemoth that was Heartbeat, the nostalgia just so happened to have a rural setting. Plotlines were not allowed to be anywhere above a minimum level of thriller, just in case someone’s geriatric gran got over-excited and keeled over.

Partners In Crime is the latest programme to be plonked in this time zone. It has all the hallmarks of being perfect for it. It is based on Agatha Christie stories, so there is crime, but not horrible levels of gore. It has that nice woman from Call the Midwife in it (Jessica Raine). It is set in the 50’s, where everybody dress smart and people were happy to live off bread and dripping. So far, so sweet.

But here’s the rub. There are attempts to create a genuine layer of menace. There are real gangsters in the East End. People who betray them are killed, with one unfortunate sap getting asphyxiated in front of our very eyes. Assassination plots are discussed and the opening shots of the Cold War are played out. There is even a brothel. Dear God BBC! Have you taken leave of your senses? Granny is having a turn and we have had to break open the cooking sherry to revive her!

It is this level of thrilling that makes the show such an odd confection. On the one hand we have a story that could be very dark, with missing girls, spies and murder. Yet the whole thing is thrown off kilter by the fact that one of the lead investigators is played by David Walliams. No disrespect to him, he has his talents, but playing a man entangled in all this to rescue a damsel from distress, even if accidentally, is not one of them. Even with his life on the line, it was impossible to fear for his survival, partly because we know there is a part 3 to this story as well as a second set of episode to come, but also because I keep expecting him to slip into a Little Britain character. It is hard to really become involved in the scene if you’re trying to work out if you should be laughing at the bumbling investigator or genuinely fearing for his life.

Despite this, it is enjoyable to watch, although perhaps in a more silly way than the cast and production team intended. And let us not forget it is being shown on a Sunday. We are always that bit more tolerant of daftness on a Sunday. Besides, your gran needs at least one night a week where she can stay up past 9.