Let’s start this week with a joke: ‘You know Mrs Kelly? Do you know Mrs Kelly? Her husband’s that little stout man, always on the corner of the street in a greasy waistcoat. You must know Mrs Kelly. Well, of course if you don’t, you don’t, but I thought you did, because I thought everybody knew Mrs Kelly.’

No, I can’t claim my sides are entirely split either. Yet, according to the first episode of What a Performance! Pioneers of Popular Entertainment (BBC4, Thursday), this sort of material by the Victorian music-hall star Dan Leno marked the birth of stand-up comedy as we know and are perhaps overburdened by it today.

The series’ stated aim is to explore mass entertainment from the days before television. But there appears to be another, unstated one as well: to show that BBC4 documentaries don’t all have to be by genial middle-aged academics keen to impart their knowledge in the form of neatly constructed arguments. Instead, they can be fun!

To this end, the chosen presenters are the unlikely double act of Frank Skinner and Suzy Klein, who bubble with a degree of chuckling enthusiasm that the average 18-30 holiday rep might envy. For a while on Thursday they were on best BBC4 behaviour, as they traced the origins of the Victorian music hall in the various strands of urban entertainment that grew up after the industrial revolution. Before long, though, the problems that would mar the rest of the programme began to surface.

For one thing, there was the surprisingly sloppy editing, with facts we’d already been told later put forward as startling revelations. For another, there was the decision to get Frank and Suzy to re-enact old music-hall turns. Seeing these turns as they might once have been was certainly necessary and even illuminating. The trouble is that, far too often, the chief focus was on Frank and Suzy’s own ‘journey’ from initial rehearsal to final performance (and their feelings about it) rather than on what I suspect most BBC4 viewers would have wanted: more on the history of Victorian music hall. It also meant that the presenters seemed to be having more of the desired fun than we were.

Stranger still, the pair apparently considered that part of their brief was to pretend that everything we saw remains pure comedy gold — up to and including that routine about Mrs Kelly (and I gave you the edited version). Throughout the programme, both presenters approvingly emphasised how irreverent the Victorian music hall was. So why treat it with such utter reverence? After all, taking an interest in the comedy of the past is not the same as insisting that it invariably remains hilarious today.

Luckily, back in 2015, our own comedy appears to be in unusually fine shape. This week, for example, saw two properly great sitcoms reaching the end of second series that were, if anything, even better than their first ones.

When I heard the premise of Detectorists (BBC4, Thursday) — middle-aged blokes potter about the countryside obsessively looking for buried treasure — I presumed we were in for a spot of easy satire where the author’s message would be something like ‘Get a life, you losers.’ In the event, this tender, kindly show has portrayed its characters as almost heroically indifferent to modern social fashions and demands. (And I bet there are far more of such people about than we generally see on television — except of course on Only Connect.)

This perspective was duly reflected in the real author’s message that came on Thursday when Andy (Mackenzie Crook) worried aloud that he wasn’t ambitious enough. ‘No shame in that,’ his friend Lance (Toby Jones) reassured him. ‘Ambition’s overrated. All these people reaching for the stars and striving to be the best. It looks exhausting.’ Not coincidentally, Crook, who wrote and directed Detectorists, turned down the chance to be in Pirates of the Caribbean 5 so that he could make the show.

With its defiant gentleness and impressive commitment to the unspoken, Detectorists mightn’t seem to have much in common with the fiercely rude and often quite lurid Catastrophe (Channel 4, Tuesday), where the central couple of Rob and Sharon (Rob Delaney and Sharon Horgan) exchange articulate, razor-sharp dialogue in even the moments of greatest marital crisis. And yet this too is an essentially sympathetic sitcom that clearly wants us to root for the characters rather than despise or pity them, as was the case with many of the comedies that followed The Office a decade or so ago. I’m not sure that two shows, however brilliant, are enough to signify a trend — but, if so, this might explain why Peep Show, despite being pretty brilliant itself, is increasingly feeling like a programme from another era.