The British sense of humour is a source of power, soft and otherwise. The anthropologist Kate Fox observed that our national motto should be ‘Oh, come off it’, and a patriotic raised eyebrow has been cited as our chief defence against demagogues. We see ourselves through a comic lens, a nation of Delboys and Mainwarings, Brents and Leadbetters, Gavins and Staceys.

But despite comedy being as central to British culture as music, books on it have few equivalents to Jon Savage’s England’s Dreaming (on punk), Rob Young’s Electric Eden (folk rock) or Simon Reynolds’s Energy Flash (rave). A nice fat volume about our national comic self-image by an astute music writer is exactly what the funny business needs. Comedy may not be the new rock and roll, but perhaps we should write and think about it in the same way.

The title of David Stubbs’s book is a nod to comedy’s current crisis. Often relegated to clip-show nostalgia for some lost triple-buttoned TV monoculture, British comedy sometimes feels like a Mallard locomotive –ripe for celebration, but we don’t make it any more. Ofcom categorised comedy, starved of slots and budgets, as ‘at risk’ in a recent study of BBC output (it’s the Beeb’s national laughter factory that’s the source of much of the comedy celebrated here). Comedy has also been unwillingly conscripted into the culture wars as chief whipping boy (or person-of-whippage, if you prefer) for nostalgic curmudgeons, even though blaming comedy for reflecting social change is like blaming a mirror because you didn’t brush your hair.

Appropriately, Different Times opens with Boris Johnson, hair as unbrushable as the demob-happy barnets of the early Goons. Johnson identified his audience-friendly inner clown early on, and adopted a catchy stage name to drive himself up the bill, as did Stan Laurel, Eric Morecambe and Syd Little. Britain is possibly the only nation to habitually vote for the funniest candidate (I don’t think Donald Trump is trying to be funny) and Johnson built a panel-game ready comic persona with the hungry focus of a circuit stand-up. Stubbs astutely notes that if you want to find good right-wing comedy look to the columnists, and Johnson’s comic voice was honed dispatching ink-spattered caricatures of Brussels politics that might as well have been Molesworth’s letters home from St Custard’s.

Opening with Johnson is a declaration of intent: this book is as bracingly political as any study of punk or Two-Tone. The focus on class – the hidden diversity challenge within comedy – is welcome and invigorating. Comics’ voting habits are dissected, but there are surprising own goals, such as missing that Dick Clement and Ian La Frenais – post-war comedy’s poets of the working class (The Likely Lads, Porridge, Auf Wiedersehen Pet) – were privately educated, or that Yorkshire-vowelled Alan Bennett wasn’t the only one of the Beyond the Fringe gang not to be officer class. Dudley Moore sits down at a Bösendorfer piano and his Dagenham roots vanish entirely.

There is some great stuff on the uneasy balance of the joy and disappointment Britain’s migrant community had at first seeing themselves on screen. For the older generation, representation was sometimes enough, while their teenage kids braced themselves for the inevitable barrage of playground abuse their classmates learned from Love Thy Neighbour. Stubbs is spot on about the 1970s sitcom Mind Your Language’s infantilisation of its impressively bilingual cast, the monolingual British teacher their exasperated imperial parent, a reflection of how so much of Britain saw, and maybe still sees, its international role. When will they learn?

Stubbs tackles the issue of Fawlty Towers’s Major Gowen and the old buffer’s notorious cricketing punchline, and bats the blame towards the writers at square leg. ‘It should have been cut. If you wouldn’t do it now, you shouldn’t have done it then.’ It’s the confident judgment of a music journalist (which Stubbs is) happy to throw his beloved Smiths’ LPs in the bin. But comedy is about shortcutting your brain, tripping it up, letting the audience fill in missing data. That requires a shared roadmap of assumptions, and precognition is no use. Writers can attempt to be kind, to educate, to change, but their jokes must use the map that their audience has brought along, not the one they hope their children might one day use.

If comedy relies on expectation and surprise (which it does), then the biggest rug-pull gag in this book comes near the end, when Stubbs reveals that he sees comedy and music as forces in strict opposition. The two, he insists, must not mix, like oil and water – or that moment when the laughter stops because Ronnie Corbett has introduced the lovely Barbara Dickson.

Most comedians, Stubbs insists, don’t have time for music. It’s a bold claim, almost Alan Partridgesque in its comic wrongness. Satire was reinvented in the 1990s by the erstwhile funk bassist Chris Morris, alongside the future Radio 3 classical music presenter Armando Iannucci. What about comedy’s multitrack studio wizard Kenny Everett? Or the pianists Hugh Laurie, Victoria Wood and Les Dawson. How about the honorary piano-Python Neil Innes, who also played guitar, like Ade Edmondson, Douglas Adams and Billy Connolly? And isn’t that Al Murray, Peter Sellers and Matt Lucas b-dum-tishing on the kit at the back? Maybe it’s why Stubbs has so little time for the comedy free-jazz of the trumpeter Spike Milligan and failed to spot the musician Dudley Moore in Beyond the Fringe next to the wordier Alan Bennett (even though the art of improvising over an agreed chord sequence explains Pete and Dud’s transcendent riffs). Stubbs is personable enough to admit that his confidence in the answer to Frank Zappa’s question ‘Does humour belong in music?’ has been shaken by two of his favourite comics: Stewart Lee and James Acaster, both music obsessives, Acaster being a drummer. The pair are also accomplished music writers; and maybe that was Stubbs’s way into suspecting there might be melody and rhythm within the comedy he loves.

I’ll say it: music pulses inside comedy. Recognising and mastering the underlying patterns is the first lesson for any wannabe musician or comedian. The abstraction is what makes music and comedy inexplicable to outsiders. ‘This music just speaks to me’; ‘this joke is just funny.’ But what makes us laugh? Surprise, repetition, patterns, delight – shock, even. Just like music.

Maybe if you can’t hear the music in comedy you will obsess instead about its lyrics. I hope that, despite the culture wars, comedy’s future doesn’t lie in the current fixation with what ‘can’ and ‘can’t’ be said. Comedy’s content, like any art form, will always be a reflection of changing society, but a racist slogan on a wall shouldn’t lead us to worry about banning paint, or walls. It’s the racism that’s the problem.

Comedy’s tones and rhythms, its chords and harmonies, can support any message you like. That’s what allows comedy to endure, despite changing times, and what makes it vital and human, and will continue to do so long after our current painstaking charge sheets of vintage blackface and scorecards for punching up or down have been forgotten.

Stubbs’s book provides a valuable record of where we are, but I hope we’ll find some new words to sing to these old tunes soon.