I had been trying to secure a ticket for Mumford & Sons’ sold-out-yonks-ago tour for most of last week. Ten minutes before they were due to go onstage for their final gig, I'd given up hope. It was a case of go home and console myself with YouTube tribute band Sonford & Mums or succumb to the touts, and who wants to give them money? Luckily a kind-hearted Samaritan with a spare pass took pity on me. Which was a huge relief, even if from my late-arrival vantage point the band was so obscured by the packed crowd that Lady Gaga might have been on banjo for all I could see.

What do you imagine a Swiss Cajun/Zydeco trio would sound like? It’s not a question that’s easy to navigate without slipping into the politically incorrect quicksand of racial or cultural stereotyping. So it gives me great pleasure to report that any narrow-minded assumptions I may have had in that department were instantly confounded by the reality of the life-affirming racket made by these three young men from Geneva as they rocked the basement bar of the St Moritz Club in Wardour Street.

If ever there was a classic case of artist and audience meeting on terribly comfortable ground, Karine Polwart's performance at last night’s fundraiser for the Green Party was it. Held in a beautiful converted church, there was more than a trace of the Vicar of Dibley lurking around the edge of the proceedings. Whatever your political affiliations, the Greens undeniably put on a good spread: it was organic beer, home bakes and Curious Colas all round, a repast matched only in its wholesomeness by a lot of thoroughly fine if sometimes overly polite musical manoeuvres.

It was Brian Wilson who started it. Eight years ago he toured Britain with a show that had at its heart a triumphant performance of his classic Beach Boys album, Pet Sounds, played – in a phrase that has become de rigueur when describing such events – in its entirety. Many more followed suit: David Bowie with Low, Sparks with Kimono My House, Lou Reed with Berlin (which in turn became a terrific Julian Schnabel film), while later this year Primal Scream will perform their epic Screamadelica album at the Olympia in London.

When I last met Nitin Sawhney, I’d heard that he was a whizz at mental arithmetic. I asked him, perhaps impertinently, what was 91 times 94? “8,827,” he relied, quick as a flash. Several hours later, I worked out he was probably right. “Vedic mathematics,” he said. What I can say about last night’s performance was there was some interesting mathematics going on. Some time signatures rubbed friskily against others in certain scenes in ways a mathematician would love. The score had an enormous facility.

The past might be a foreign country but sometimes they don't do things so differently there. Two decades ago I found myself backstage at Wembley Arena discussing music with one of MC Hammer's rubber-limbed dancers, nicknamed No Bones. Who was his favourite band? A bunch of geeky white Brits called Depeche Mode, who, I discovered, were a huge influence on the Detroit Techno scene. Twenty years on it is payback time. Detroit Techno is now a huge influence on another group of geeky white Brits, Hot Chip.

Here’s a deceptively simple question. What is African music? Does a band make African music simply by dint of the fact they come from Africa? One of last night’s three African Soul Rebels acts was South Africa’s Kalahari Surfers. Ensconced behind a table’s worth of laptops and other gismos, they made subtly menacing, dubby rock with an early '80s slant. And in fact they did it rather well, conjuring memories of Gang of Four and their ilk.

There is something eternally refreshing about catching a band on the first show of their first tour after the release of their first album. Banter remains untarnished by overuse; smiles appear spontaneous and gratitude genuine; mistakes are swatted away with a giggle and a sly curse. Hope – that most intoxicating of emotions – fills the air like the scent of fresh cut grass.

The death at the weekend of Doug Fieger, the co-founder of The Knack, meant that melodic US pop had lost a fine exponent. But more than 30 years on from the eternal über-hit "My Sharona" the appeal of infectious hook-lined music lives on in the work of preppy foursome Vampire Weekend, who have made their name by mixing new wave revivalism with African beats, dubbing their style “Upper West Side Soweto”.