Mozart's La Clemenza Di Tito was written in the last year of his life around the same time as Die Zauberflöte, the Clarinet Concerto and the Requiem, when Mozart was at the height of his powers. Which is just as well, because he wrote the vast majority of it in a little over two weeks, finishing with just a week to spare before the event for which it was commissioned: one of the coronations of Emperor Leopold II. While Mozart's status as an infant prodigy is well remembered, to produce a full length opera of such quality under such time pressure seems an even more extraordinary feat.

La Clemenza didn't get off to a good start: the Empress loathed it. But the opera was a huge success for many years after Mozart's death and, after a long lull, has been undergoing a bit of a revival recently. On the basis of last night's performance by Hampstead Garden Opera, I can see why.

First things first: I deeply love seeing opera performed on a small stage, and it doesn't get much smaller than the upstairs theatre at the Gatehouse, my local pub in Highgate, which seats about 180. The immediacy and directness is enormous, you can hear all the words without the singers straining excessively and there's a requirement that they actually act. I've now seen several HGO performances here and thoroughly enjoyed them all - in many ways, far more than going to a full scale opera house.

In this performance, both singing and acting were outstanding, especially from two young French singers. Elisabeth Poirel was a wonderfully scheming Vitellia, and Sylvie Bedouelle's Sesto was glorious: both packed real vocal firepower, nailing every note in the middle in arias of elegance, beauty and ferocious technical difficulty. The Mozart-period costumes were jaw-droppingly sumptuous (with a bit of help from Glyndebourne, apparently - it's just you don't get to see them up close at Glyndebourne). If I have a complaint, it's with the orchestra: intonation was poor much of the time and there were enough squeaks and fluffs to be distracting.

However, both conductor and director kept everything moving briskly and effectively, which can't be easy in this opera. There are several long recitatives, which I personally love but aren't always to everyone's taste, the character of Titus is a cardboard cut-out of a paragon of justice rather than any attempt at a picture of a real Roman emperor and the action gets a bit static in Act 2. At that point, however, the transcendence of the music and the virtuosity of the arias kick into high gear. By the time of Sesto's Rondo "Ah for this single moment" (Deh per questo istante solo) and the closing sextet "You forgive me, Caesar" (Tu, è ver, m'assolvi, Augusto), I was completely bewitched.

And by the way, credit to HGO for some fantastically informative programme notes, with masses of fascinating information. At £1 a programme, it puts the bigger opera houses to shame.

Hamsptead Garden Opera's La Clemenza di Tito is playing until 2nd May at Upstairs at the Gatehouse, Highgate, London 24th April 2010