Cinderella goes to the square

Sweetheart American mezzo Joyce DiDonato stayed firmly behind the proscenium arch for yesterday evening's Royal Opera performance of Massenet's Cendrillon - reviewed by theartsdesk on its opening night - but another Covent Garden regular, former ballerina and non-irritant presenter Deborah Bull, was soon schmoozing the crowds in Trafalgar Square, assembled to watch the fairytale unfold in real time beneath Nelson's Column. It was a big occasion for the long-deceased composer, who having enjoyed short-lived fame went into near eclipse except for Werther and Manon over the next century but last night supposedly had 50,000 pairs of eyes up and down the UK on one of his most delicate creations courtesy of the free BP Summer Big Screens.

I had fond memories of the last time DiDonato loomed large in Trafalgar Square as a famously wheelchair-bound Rosina in Rossini's Il barbiere di Siviglia back in 2009. So I was happy to join a friend's family and sit on the precious inflatable cushion which has buffered me against some of the worst bus journeys in the world, nibbling sushi while Joyce's Cinderella - obviously in better voice than on the first night - and her Prince Charming in a thousand, the stunning Alice Coote, went through their paces. And yes, this crowd was any demographer's dream: all ages - though mostly young - and all colours. It chattered, texted and mobiled furiously for the first couple of minutes, but soon settled into spellbound near-silence - proof that any top-notch piece of performance art will catch even the most casual onlooker's imagination.

They were charmed by director Laurent Pelly's wacky imagination and surreal costume designs. They found the idea of a lady in trousers as the Prince a bit odd - no one remember the panto tradition? And though the short break between Acts I and II lost quite a few punters and the general level of concentration, that didn't matter too much and everyone had settled down nicely by the time of the love duet (pictured right). One serendipitous touch was the D-bell of St Martin-in-the-Fields chiming eight just as Cinderella settles down to sleep - and perfectly in tune with the mood music, striking the dominant.

Water supplies, free macs and cushions - I needn't have brought my own, though I'm very attached to it - gilded the occasion, despite the windy and mostly grey evening. Sponsors BP were not allowed, however, to get off entirely scot-free; a group to be found at www.bpwhiteswan.org had put together an articulate campaign leaflet asking us to "enjoy the performance" but "remain aware of the hidden agenda of companies like BP and Shell". And it did it with a clever Swan Lake scenario in which Rothbart stood for "the murky and sinister side of one of our favourite corporations". Some copywriter in the organisation knew its market. And it wasn't screaming too loudly about it, just concluding that "without oil sponsorship we'll have to find ways to support our Royal Opera House (or the National Gallery, behind you) without taking money from destructive corporations: a difficult task, but by no means impossible". Lesson over (there was a five-minute performance, too, though I must have arrived too late to see it); and it didn't stop us relishing the big show. Another vital result of all this: there hasn't been a DVD of Massenet's Cendrillon available, a lack I felt when I was taking my opera appreciation students through it, but thanks to this there will be soon.

• Further performances of Cendrillon at the Royal Opera House listed on the RO website
• theartsdesk chooses the best of the Royal Opera and Royal Ballet 2011-12 season