They may have been each other's bitter nemeses for over a decade, but Gary Barlow and Robbie Williams are a classic cop-show duo: the square rule-follower and the loose-cannon clown who, between them, somehow get things done.
Barlow is the straight-laced Cameronista who's just been to the Palace to receive his OBN, Williams the cartoon bad boy who partied so hard for a few years either side of the Millennium that he's not even allowed to sniff the hard stuff any more. And, with Take That's reunion done and dusted for now, they're both in solo action once more.
Gary Barlow, the establishment man, turns up to Mencap's Little Noise sessions in a bank clerk's suit and back-to-school shoes, looking for all the world like he was dressed by his mum. A conservative cheesemeister to the core, the real-life Phoenix Nights turn who made the big time, he's happiest when sat at the BabyBel ... sorry, baby grand. Even his piano freakout is punctiliously precise, more courtroom stenographer than Jerry Lee Lewis.
Weirdly, given that he wrote these songs and must have sung them thousands of times, he uses an autocue as he runs through a sequence of segued ballads which, in a gag for X Factor viewers, he describes as "a medley, not a mash-up". He's clearly got a bee in his bonnet about recent eliminations – and survivals – on that TV show. The echo on the mic, reminiscent of the Tannoy at a 1950s Butlin's swimming pool, may make him almost incomprehensible, but there's no mistaking his description of Essex costume-horse Rylan Clark as "absolute shite".
It's another X Factor contestant, however, who comes to mind as Barlow stands up to tackle "Candy", the recent No 1 he penned for Williams. Collagen Westwood, harshly thrown out for having a sip of Jack Daniels before her sing-off, delivered the offhand put-down "it's not as if Gary Barlow is the Holy Grail of singing anyway". Judging by his wavering attempts to reach the high notes, Collagen was bang on the money.
What he can do, to everyone's astonishment, is dance. Showing impressive flexibility for a man of 41, and a self-aware sense of humour that's completely out of character, he breaks off between each verse of "Pray" to execute the full Nineties choreography, complete with semi-splits.
The congregation at St John's, one of their number bearing a "Sorry God, We Worship Gary" sign, lap it up. And there comes a point – whether during "Patience", or "Back For Good", or "Greatest Day" – when even a Barlow-sceptic has to acknowledge that, my God, that boring bastard can write a song.
No royal honours for Robbie Williams. As if to highlight the contrast between Barlow's encounters with the Queen and his own, he tells the 02 "She hasn't got a frigging clue who I am."
Robbie at the 02 inevitably involves more bells, whistles and whizzbangs than Barlow in a church: there are dangling LED signs, a massive hydraulic crown and mirrorball effigies of his own head. And also more (extr)overt showmanship. Making a boxer's entrance through the crowd in a black suit and Converse sneakers, he mounts the in-the-round stage, does a Mussolini strut around its perimeter, then we're straight into "Let Me Entertain You". From this moment on, Williams, seemingly lost for years in his offstage life (though not any more, to judge by a sentimental speech about his two-month-old daughter), is in his element.
The highlight of the greatest-hits, filmed-for-TV set is probably the berserk flaming church window in front of which, perched on a pulpit, Williams preaches the gospel of Take That. "In 1989, early 1990, a man in Worsley, Manchester, had an idea ..." Nigel Martyn-Smith's idea, Robbie deadpans, was to create a boy band who could be "as big as New Kids on the Block".
The asides and ad-libs are more fun than the music. "I've sung some songs that were lame ... (Personally I think that the album Rudebox was an underrated classic)/I've slept with girls on the game ... (Or, strictly speaking ... not on the game. Go on, Twitter that ...)"
Guy Chambers, Robbie's songwriter through most of the glory years, is brought on to accompany him on piano for a short stint. Later, as the entire arena echoes to "Angels" – an overplayed anthem whose greatness one has to acknowledge, even through gritted teeth – your mind wanders back to Chambers and, once again, you concede: my god, that guy can write songs too.
A double treat for horror-metal fans as Marilyn Manson and Rob Zombie embark on their Twins of Evil tour at The O2, London (Mon); Manchester Arena (Tue); Glasgow SECC (Wed); and NIA, Birmingham Thu). The North Sea Scrolls give an alternate history of the British Isles at the Trades Club, Hebden Bridge (tonight); and the Deaf Institute, Manchester (Mon).