'Who here has been dragged along and doesn't have a f****** clue what's going on?' asks Darren Criss after the first number. He and Michele have already established whose seen the duo sing before, who hasn't but is excited to be here – and this last question prompts a cheer from a guy in the stalls, who raises his pint in salute. 'Well in that case, I'm Idina Menzel,' says Michele – 'and I'm Nick Jonas,' quips Criss, 'if you don't like it, tweet them.'

Not liking this show is, for the crowd of devoted fans, not an option. Or indeed, surely, for pint bloke – because the joy of music sits squarely at the heart of Michele and Criss' gig. Not to mention two sets of vocal pipes that can squeeze your heart or blow you away depending on the track.

They set out their musical theatre stall early, opening with 'Broadway Baby' from Follies followed by 'Suddenly Seymour' from Little Shop of Horrors. The mood is informal and relaxed, with Criss strolling on stage wearing jeans and a plaid shirt and Michele in a beautiful floor-length dress, but flashing the leggings underneath she's put on to combat the cold. For this, lest we forget, is Lea Michele and Darren Criss, not their Glee characters Rachel Berry and Blaine Anderson, all pristine clothing and slicked back hair.

But 'Gleeks' are well rewarded for their loyalty, with a clutch of hits from the show, including Berry's signature song, 'Don't Rain On My Parade' and Anderson's cover of Katy Perry's 'Teenage Dream'. Blending show tunes and chart toppers defined Glee for six seasons, and now makes for a dynamic set list when interspersed with Michele and Criss' solo material.

And yet, the stand-out highlights of the night had little to do with Glee or the duo's recent personal output. Proving his knowledge and passion for music extends way beyond the Broadway stage, Criss does a whistle-stop tour of Scottish pop music, finally resting on a Chvrches number. Then, joined again by Michele, they do sweet, sweet justice (and even improve on) Lady Gaga and Bradley Cooper's 'Shallow'.

If proof were needed that we were in the presence of true artists, the night closed with an acoustic version of Adele's 'Make You Feel My Love' (especially poignant for Glee fans, who watched Rachel Berry/Lea Michele sing it after the death of her partner Finn Hudson/Cory Monteith). No microphones or amplification needed, just two voices and Criss' guitar filling the entire Clyde Auditorium with talent.