Pop-Up Opera doesn’t make life easy for itself in its choice of venues, but when it comes to staging a comic masterpiece such as Rossini’s Il Barbiere di Siviglia, that only means more laughs for the audience.

The first night of its summer tour of ‘The Barber’ was down the circular shaft of Isambard Kingdom Brunel’s tunnel under the Thames at Rotherhithe. Down went the audience, down went the cast, and in a drum-like space with no wings, the cast gamely set about Rossini’s fiendish and fun-filled score with cheerful elan.

It’s the usual story of a nobleman disguised as a poor student (and drunk soldier, and pious music teacher) who woos the imprisoned ward of a jealous old guardian and liberates her with the help of a barber-surgeon. Not so usual, then, perhaps, but none of it matters – it’s just a wonderful excuse to sing arias at breakneck speed, and to muck about in an impossibly small space. And that adds up to a delightful, genuinely funny evening for an audience that clearly prefers underground to mainstream – literally, in this venue.

This production is double-cast – there are a lot of dates, around and outside London – but outstanding in the first-night line-up were the Norwegian baritone Leif Jone Ølberg as Figaro, the resourceful barber of the title, and the British baritone Alistair Ollerenshaw as the jealous guardian Bartolo. Warm-voiced mezzo-soprano Katie Slater has a very game, Miranda-like gift for clowning around, and it was a treat to hear the downtrodden housekeeper Berta’s sole aria, sung so musically, by Emily Blanch.

Musical director Berrak Dyer at the piano and James Hurley, directing, do a fantastic job, and the English captions for the Italian libretto are a real bonus. Instead of a slavish, word-by-word translation, up popped hilarious summaries and occasional dual texts, so that we could enjoy the Italian too, and irreverent asides (although the world may not be ready for jokes about the Zika virus).

Anyone tired of overstuffed opera should catch this production, in which Bartolo is tagged #creepy, the suitor is introduced as “the famous celebrity that everyone has heard of”, and, his true identity as a nobleman revealed, admits to his love that “I’m the same person – just with loads of money, fame and power. Forgive me?”

As they certainly didn’t say in the 19th century, what’s not to like?