Birmingham's A Boy was Born celebration of the Benjamin Britten centenary continued last week with the CBSO presenting two of his rarer works, one of them infrequently given, the other a genuine rarity.

The reason we don’t often hear the Rimbaud song-cycle Les Illuminations is just because it lies too darn difficultly on the voice. The hallucinatory texts draw tortuous melismas and indeed notated drawlings from the composer, putting the singer under a huge amount of pressure within the tightly rhythmic context of Britten’s scoring for string orchestra.

Tenor Ian Bostridge achieved the task magnificently. He has a mesmeric stage-presence (in recital he leans and swivels, one hand fulcruming on the piano: here he eyeballed the orchestra, who collaborated so sensitively).

Consonants were spiky and well-sprung, mood-changes were mellifluously encompassed, and Bostridge’s duet with concertmaster Laurence Jackson in “Antique”, the singer’s hands in pockets, was a masterpiece of performance-delivery.

Much more of a rarity is the Prelude and Fugue for 18 Strings, composed for Boyd Neel’s crack string orchestra; whatever those players’ accomplishments, they were certainly surpassed here.

The Prelude was taut and glassy (more wonderful solos from Laurence Jackson), the Fugue bustled impressively, everything judiciously-balanced under the baton of Michael Seal, CBSO associate conductor, and also a member of the orchestra’s second violins – so he knows his stuff.

Britten was framed by Elgar, beginning with the exhilarating Overture In the South, lithe, alert, orchestral colours emerging from within the textures, and with a lovely viola solo from Chris Yates. I relished the growling timpani and bass drum.

And we ended with the Enigma Variations, cogent, well-crafted, enriched by Seal’s insider’s detail, sensitively nuanced – but ultimately failing to catch the heart, efficiency scoring over emotion, school of Boult rather than school of Barbirolli.