Les Boréades, Rameau's final, most innovative stage work, was never seen in his lifetime. The story of Alphise, Queen of Bactria, who abdicates rather than marry the suitor that tradition dictates, was decidedly risqué for the French court in 1764, with the Revolution just around the corner. Even now performances of the complete, three-hour work are rare, but it has been heard before at the Proms, in 1978 when it was conducted in concert by John Eliot Gardiner.

Even though the coaches parked nose to tail in Kensington Gore on Saturday turned out to be delivering middle-aged pilgrims to the shrine of the Blessed Cliff in Hyde Park, there was still a sell-out across the road, thanks to a chance to hear Cecilia Bartoli make her Proms debut. A singer born to charm an Albert Hall audience if ever there was one, Bartoli didn't disappoint, producing performances of superlative technical finish and musicality, and turning what was sometimes unpromising raw material into purest gold.