Theatrical vintage radio comedy thrillers hardly being a dime a dozen, you might think we wouldn’t need to complicate things. You would of course be wrong.

The Fitzrovia Radio Hour’s universe, which has come into being over two years of successful London shows, is a complicated one.

Take the five performers you see before you, frantically playing out their thrillers, romances and horror stories while creating their own sound effects in a ration-era British answer to Hollywood Star Playhouse and other American shows. These actors have no idea they are playing to a modern audience. And they take their work very seriously. Fortunately, modern audiences seem to find this very funny indeed.

So far, so clear as mud. It thickens. Most of The Fitzrovia Radio Hour’s props – the spinning top that imitates a speedboat failing to start, the Bakelite hairdryer that plays a heating torch, the ubiquitous cabbage – are of the era or just after it. Or, in the permissible case of the cabbage, of a type that was available at the time.

But then, sometimes we employ Bubble Wrap, which was invented in 1960. Such an obvious anachronism might seem to go against an aesthetic so carefully created. However, we are nothing if not opportunistic and the effect on an audience of twisting a roll to make the sound of a violently broken neck seems to compensate.

Similarly, a humble sheet of Perspex can indicate a tear in the space-time continuum that has created an evil Nazi doppelganger, simply by being wobbled frantically. And Perspex turns out to have come on to the market in 1933. Confused?

Perhaps it is best said that The Fitzrovia Radio Hour is something of a Chinese puzzle: beautifully simple on the outside, fiendishly complicated within. For instance, did such classic BBC announcer’s tones, stiff of lip and firm of imperial purpose, ever advertise carbolic soap, cigarettes, bile beans and tobacco?

No. But we never said they did. We just say they do, where we’re broadcasting from. Which is a place where intrepid pilots break the sound barrier in RAF prototypes played by desk fans, where strange creatures from beneath the Thames are conjured up with only a bowl of jelly and a plunger, and where murderers plot, act and are arrested within a four-minute timeslot, all thanks to the cunning swapping of hats.

The Fitzrovia Radio Hour exists in a kind of time-lapsed alternative universe. With cocktails.