Wonderful Two-Headed Nightingale, a new double concerto by British composer Luke Bedford, is a bold, dense and arresting blast of a composition – a work that forcefully reiterates Bedford's voice and brilliantly showcased its fine set of players. Commissioned by the Scottish Ensemble and inspired by a 19th-century poster of singing Siamese twins, ferocious open strings set things thrashing into motion. "As soloists, it's as if we're joined at the hip", explained the Ensemble's director Jonathan Morton, and he and violist Lawrence Power spent the remaining 13 high-octane minutes in searing unison. The accompaniment piled microtones into blocks of bright primary colour; inner parts and brute energy kept things surging forward but – as in his opera Seven Angels – Bedford's knack is for creating atmospheric sustain rather than long-span narrative. The scoring is for the same lineup (strings plus oboes and horns) as Mozart's Sinfonia Concertante, which ended this programme. Cool or detached this was not; Power and Morton each have the imposing charisma to make every phrase their own, and they blurred the line between playful responses and one-upmanship. In this music, which Mozart wrote to prove his own talent, such machismo swagger makes some kind of sense.

Earlier, William Alwyn's lush and yearning Pastoral Fantasia proved a luxuriant solo turn for Power, who must have the most seductive viola sound in the business.

The Scottish Ensemble were on top form: they play with such uniform conviction that their guest wind and brass seemed grafted on. While the Alwyn had the warmth of a full orchestral string section, Haydn's Symphony No 44 fizzed with dry-bowed virtuosity, as lean and lithe as a baroque concerto grosso.