Ian Bostridge's Ancient and Modern project at the Wigmore Hall promises, among other things, period and modern instruments in the same concert, but it opened with this purely baroque programme that resolutely represented the former.

The period instruments were those of the English Concert, on impeccable form under their artistic director, Harry Bicket, though some of the works were undoubtedly player-stretching. The focus was on Italian composers, with the German-born Handel (who perfected his art in Italy before transferring it to England) and the obscure, Hanover-based Francesco Venturini the odd men out.

The sinfonia to Alessandro Scarlatti's serenata Clori, Dorino e Amore began with a slow, powerful chordal section in which the band's richness of tone made a distinctive impact. They were near-virtuosic in the helter-skelter scales of the follow-up fast section, a feat they bettered in Handel's motet Silete Venti in the second half. Oboe player Katharina Spreckelsen brought a potent, tangy tone to bear on Vivaldi's characterful D minor Concerto RV454, and a sonata (actually more like a concerto or suite, as Simon Heighes's programme note pointed out) by Venturini proved a worthwhile discovery.

Bostridge was frustratingly uneven on this occasion. Neither of the major works he sang - the Handel cantata, or Scarlatti's work on the Orpheus theme, Dall'oscura Magion - was written for tenor voice, and in these transposed-down versions, his bottom notes came close to vanishing point. In places, his colouristic palette was limited, and neither his tonal range nor his vowels sounded authentically Italianate.

Yet he was at his best in the second aria and final Alleluia from Silete Venti, where his long-breathed phrasing and neat, regular runs were admirable; though in his first encore, Scherza Infida from Handel's Ariodante - once again not tenor territory - his heightened expression registered as too mannered.