Simone Kelner: So, come on, come on, do the locomotion with me

Once in a while, something happens that restores your faith in humanity, or gives you an unexpected thrill, or leaves you with a semi-permanent smile on your face. The 9.53pm Virgin Trains service from Stoke to London Euston was, on the face of it, an unpromising venue to have such a life-affirming encounter, but there we were, minding our own business, unscrewing the odd bottle of buffet wine, when something extraordinary happened. A five-piece band suddenly emerged in the aisle next to us and struck up the Louis Prima classic "Buona Sera Signorina". Magical was the only word for it. They were on their way back from a gig in Manchester and, so in love were they with the music, or maybe the smooth ride of the Pendolino train, or life itself, that they just couldn't stop playing. In fact, "intoxicating" was another word for it, given how powerful seemed their desire to use music to make people happy, even in the most unlikely situations. Through a repertoire that included the Beach Boys, Queen and Katy Perry, they harmonised their way through Milton Keynes Central and Watford, turning the whole of carriage C into a karaoke-ing, foot-tapping, clapping throng. They turned out to be called the London Essentials, effectively a busking supergroup, or a pop-up band, if you like, who mainly play at private parties – they'd just been hired as the turn for the launch of a new Mary Portas outlet, so they're not proud – but further investigation revealed that they also like ad hoc gigs in the streets of Soho, once stopping the traffic in Frith Street.

It helps, of course, when you're an acoustic band and travel light. "No volume issues, no travelling restrictions," proclaims the band's website. "No social barriers between band and audience" – we can vouch for that, given that some of them were virtually sitting on the laps of our female colleagues for a couple of numbers – "providing an exclusive, bohemian, humorous and mystifying experience for any event". But what made this such an uplifting experience was not just the unexpected treat but the sense that we were all, passengers and band, breaking the rules. At any time, we thought we would be told off by the guard and instructed to desist, or the train would be boarded by British Transport Police to inform us that we were breaking various by-laws relating to the performance of live music in a travelling conveyance. But no. Quite the opposite, the lady in charge of the refreshment bar – or Betty Buffet as she came to be known – was such an enthusiastic participant in the whole crazy scene that she allowed us to broadcast the performance to the rest of the passengers through the public address. I don't know what anyone else thought of it, but it must have made a welcome change from the constant announcements about hot and cold drinks and the instructions to take your belongings with you. Not to mention the usual soundtrack to an inter-city journey: "I'm on the train..."

Have a tuneful weekend.