Proms 30: BBC SO/ Davis, Royal Albert Hall, London/Radio 3

As the temperature soared, come 7.30pm, there they all were in the Royal Albert Hall: Dame Felicity Lott, tremulous in boudoir gown, Sir Andrew Davis and the BBC SO poised in white tuxedos, the ranks of the Trinity Boys' Choir, Cantate Youth Choir and BBC Symphony Chorus all immaculately arrayed to deliver a by no means obvious programme to what proved to be a substantial and highly appreciative audience.

The focus was the French language: Poulenc's setting of Cocteau's monodrama La voix humaine (1958), and Stravinsky's part-spoken, part-sung treatment of Gide's verses for his dance-melodrama Perséphone (1934).

Gide notoriously took against Stravinsky's deliberate distortion of French accentuation for his own rhythmic purposes, yet, in a sense, the more perverse of the two projects was Poulenc's attempt to set, as song, a text that depends so intensely upon spoken nuances, as Cocteau's lady-protagonist desperately attempts to win back a defaulting lover in a much-interrupted phone call of which we hear only her side.

True, Poulenc strongly identified with the protagonist, and the extreme responsiveness and skill of his setting won a declaration from Cocteau that he had fixed definitively how the text should "go". But it results in a vocal line of incessant nervousness, with little room for expansive lyricism - a fragmented continuity which Poulenc's pungent harmonies and incisive orchestral scoring can only partly offset, so that everything ultimately depends upon the precision and conviction of the singer.

But, as she alternately paced around and slumped upon her chaise longue, cradling her telephone, Dame Felicity called up that precision and conviction with mounting intensity, appearing, by the end, quite overcome herself.

The second half of the programme, Perséphone, was Stravinsky's only large-scale French-language project, and although he had to incorporate long tracts of flowery spoken declamation for the exotic Ida Rubinstein (who commissioned the piece for herself to mime and speak), he also managed to absorb something of Debussy, Fauré, even Massenet, without ever actually sounding like them, so that this alternative Rite of Spring has a gentle radiance unique in his output.

At first it seemed that Sir Andrew's restrained direction and Nicole Tibbels's somewhat understated recitation were likely to result in too gentle a reading, lacking something of Stravinsky's compensating incisiveness of articulation. But with the fine-grained narrations of the tenor Paul Groves, and the heart-stopping entry of the children's choir, the piece gained in gravity, culminating in a luminous sublimity of sound and feeling that this Proms season is unlikely to match.