Many is the pop star who has craved gravitas. Only Sting, however, has pursued it by covering John Dowland on an album on which he played the lute. Only Sting has released an album of winter-themed madrigals. Only Sting has written a musical about the closing of the shipyards in Wallsend. He’s the rare pop star who could, should he wish, have a pop at Slavoj Zizek for being just a bit too populist and crowdpleasing. All of which makes his current activities — an album and a tour with Shaggy, the reggae star who’s the reduced-for-quick-sale ready meal of the genre, and a man who is to gravitas as Chris Grayling is to competence — rather astonishing.

That they paired ‘It Wasn’t Me’ and ‘Every Breath You Take’ late in the show was surely not just about these being their best-known songs. Both are about jealousy and spying, but whereas ‘It Wasn’t Me’ is a Carry On film of a song (Shaggy’s persona is that of a Jamaican Sid James) in which our hero is caught ‘banging on the bathroom floor’ by a girlfriend who ‘even caught me on camera’, ‘Every Breath You Take’ is a sly and unsettling lyric about jealousy and control, paired with a taut, coiled melody. It’s the best song Bryan Ferry never wrote.

Side by side, the two tracks suggest that while to Shaggy everything is a joke, to Sting nothing is a joke. Perhaps, though, he’s had enough of being pop’s Mr Po-Faced. He headed back towards more straightforward pop on the 2016 album 57th & 9th, and the album with Shaggy — 44/876 — took him back to the UK top ten last year for the first time since 2003. The problem is that the songs on it are nowhere near as good as either Shaggy’s solo hits — which, for all their grindingly obvious sexuality, are at least fun — or Sting’s songs. It’s as if Sting has sanded down Shaggy’s lubriciousness, while Shaggy has broken Sting’s focus. There were moments when one thought: honestly, how has it come to this? Did Sting ever think he would be taking the role of a sidekick called Rayvon, playing an old Steve Miller bassline as Shaggy performs ‘Angel’ in front of him?

There were moments of unintentional bathos, too. Presumably Sting was dressed all in black, and Shaggy in some diaphanous white affair, to highlight the fact that, you know, we’re all the same under the skin. Ditto Shaggy’s speech about coming together despite our differences. Ditto the snippet of Bob Marley’s ‘Get Up, Stand Up’ that pops up in ‘Walking on the Moon’. But this was an audience that was not just all the same under the skin, but all the same on the skin, too. None of them were likely to have to stand up for their rights on the way home.

‘Reggae people!’ shouted Shaggy at one point — he shouted a lot, often at times when one wished he wouldn’t — and they cheered, possibly because this was the only time in their life they would be called reggae people.

Inevitably, it was the old Police songs that got the biggest cheers and the cameraphones held aloft. They simply sounded sharper, clearer and more direct than anything else. ‘Walking on the Moon’ — all empty space, living up to its title — was glorious. And both ‘Every Breath You Take’ and ‘Can’t Stand Losing You’ (narrator threatens to kill himself to make his ex feel bad) reminded one what a peculiarly vindictive songwriter Sting was before he decided that if you loved someone you should set them free.

It wasn’t a boring two hours, by any means. Just a very odd two hours. Still, at least there was no lute.