And then there were three…

At least that’s the current headcount in this stripped-down version of UB40 that features the unmistakeable vocals of Ali Campbell and Astro plus the keyboard talents of Mickey Virtue.

The trio were reunited in 2013 after leaving the original line-up and have been making music together ever since and, last night at Rochester Castle Gardens they proved that, like a fine red, red wine, they just get better with age.

The show quickly sold out proving that the lads from Birmingham born with reggae in their veins are as popular now as they ever were and with good reason, because it’s safe to say that to truly revel in the rich tones of Ali's unmistakable vocals you really have to hear him sing live.

Before UB40 featuring Ali, Astro and Mickey – there are about a dozen or so very good reasons why they can’t call themselves simply UB40 – took to the stage a question that’s oft haunted many a music-lover was finally answered: What would Prince's Purple Rain, widely regarded as one of the greatest albums ever recorded, have sounded like with a reggae lilt?

Support act Radio Riddler supplied the solution to that particular conundrum. Their first full-length album consists of a complete reggae makeover of the much-missed diminutive superstar’s aubergine-hued masterpiece called, appropriately enough, Purple Reggae. It features guest vocals from Suggs, Ali Campbell, Sinead O'Connor, Citizen Cope, Beverley Knight and Deborah Bonham – the sister of legendary drummer John Bonham – and was launched to coincide with the 30th anniversary of the release of Purple Rain.

The band, made up of Brian Fast Leiser and Frank Benbini from Fun Lovin' Criminals, gave the expectant audience a taste of their take on Prince’s finest with a few songs from their album including a surprisingly workable version of the title track itself. They even managed to provide their own twist to the iconic guitar solo using, instead, a trumpet.

After a brief instrumental introduction Ali and friends were quickly into their stride with a few classics from their substantial back catalogue –Here I Am Baby (Come and Take Me), Wear You to The Ball, One in Ten and Cherry Oh Baby – that had the audience up on their feet straight away.

Just another Girl and Rat in Me Kitchen, the song that no one can resist singing along to without adopting a desperately inappropriate Jamaican accent followed.

Next up for a boisterous crowd that simply hadn’t stopped bouncing since the opening salvo of classic UB40 was She Loves Me Now, a track from their latest album, Real Labour of Love, which sits proudly at number two in the charts.

It proved to be one of those moments during a concert – and they all have them – when there’s a dip in audience energy, a thinning out of numbers as the less fanatical of fans pop off to replenish their food and drink supplies, or take care of other, equally as important, tasks.

That very slight lull continued through Silhouette and Hard Times but, once the familiar opening strains of Kingston Town echoed across the spectacular venue of Rochester Castle Gardens the crowd have found their voices – and started to demonstrate a remarkably unchanging array of dance moves – once again.

By the time Ali launched into Many Rivers To Cross the place was absolutely bouncing but this song proved to be just the first of a crowd-pleasing crescendo that also included the stark, unflinchingly raw Food for Thought, the surprisingly upbeat but tender cover of Elvis Presley’s Fools Rush In and, of course, to wash it all down there’s nothing like a nice rich, full-bodied red, red wine and that’s exactly what a jubilant audience was served up.

Despite the recent changes to their line-up, this is a band that continues to attract a diverse audience, from young to old and, without fail, it’s invariably their older music that stirs the souls, the feet and the vocal chords of their legions of fans.

There’s certainly new music on show, but the three young men from Birmingham know their audience well – and so they should after performing to a great number of them for the past 40 years – and they never fail to give them exactly what they want.

Our evening with UB40 featuring Ali, Astro and Mickey was like a stroll down a wonderfully evocative, sometimes poignant, always magical musical memory lane.

One in 10? These boys are one in a million!