Scottish Ensemble / Morton, Wigmore Hall, London

The Wigmore Hall is celebrating the legacy of the Swiss conductor and patron Paul Sacher (1906-99), who used the millions he married into to commission a string of modern masterpieces from Bartok, Strauss, Stravinsky, Carter, Boulez, Britten et al, and left a research foundation in Basel stuffed with sketch material and memorabilia. This visit by the 12 strings of the ever-welcome Scottish Ensemble led by Jonathan Morton brought forth three of Sacher's best.

They opened with Stravinsky's 12-minute Concerto in D (1946). Its deceptively lightweight neo-classical mannerisms mask a steely concentration of thematic working and some remarkably acidulated harmonic progressions. Here, the Ensemble's precision of attack and wiry vigour of timbre – with just a touch of sweetness in the swooping intervals of the middle movement melody – were exactly what Stravinsky would have wanted.

After which Metamorphosen (1945), Richard Strauss's seamless half-hour elegy on the sad destruction of Germany's artistic heritage in the dying months of the Second World War, could not have come as a stronger contrast – even, as heard here, in the rediscovered sketch score for seven solo strings from which he elaborated his more familiar version for 23 strings.

If one sometimes missed the fullness of the latter, if the incessant elaboration of Strauss's melodic lines and subtle shifting of his harmonies stretched these players' control of phrasing and intonation to the limit, the intricate thematic working came over all the more clearly. And the ebbing of the music, with its funereal citation from Beethoven's "Eroica", into darkest C minor was unforgettable in its hushed finality.

Bartok's Divertimento for String Orchestra (1939) also centres on an anxiously elegiac slow movement belying the work's title. But then, it was composed in haste on the eve of the outbreak of the war in a retreat provided for him by Sacher shortly before his flight to America. Nor are the outer movements, for all their folkloristic charm and gutsiness, without their tensions – the finale sounding at one point as though invaded by a swarm of wasps. Morton however, audibly revelled in its contrasts, setting the finale going at an almost reckless pace without missing a colouristic trick.