Having covered already Holmboe’s first and last published thoughts on the string quartet genre (omitting the 10 or so fragmentary works pre-No 1) in previous releases (3/21, 8/22), the Nightingale Quartet’s third volume continues to juxtapose early and late from his catalogue. Holmboe refined rather than evolved – for that we will need to hear those rejected essays – his view of the medium as a whole. Just as with the quartets of Shostakovich and Robert Simpson, there is a palpable sense of private dialogue at play here, of persuasion rather than the oratorical utterances of the symphonies. Mind you, Holmboe as a composer rarely needed to raise his voice.

No 4 (1953 54, rev 1956) is cast in five movements – a favoured format (cf Nos 3 and 8, for instance) – though not arranged as an arch form as in No 3. Its sequence of andante-presto-adagio-largo-allegretto is unusual in structure, with the Presto espansivo the longest movement (the Nightingales taking the composer at his word, running half a minute longer than did the Kontras) and the Largo e semplice by far the shortest (around 105 seconds in duration). Dedicated to the composer’s pupil Per Nørgård, the Fourth is one of his finest works, a peak in his cultivation of the ‘metamorphosis’ technique that underpins so much of his output.

No 4’s serene atmosphere – notwithstanding some volatile episodes along the way – persists in its immediate successor (1955) which, nonetheless, feels like a completely different conception. Its three movements (fast-slow-fast) are a masterclass in quartet-writing as well as joined-up creativity. Its perfection of form is matched by its concision: 20 minutes here, slightly swifter than the Kontra, mainly in the opening Pesante-fluente. No 16 (1981), in an anything but standard four movements, shows that while Holmboe’s style had outwardly not changed that much, events below the surface had moved on. Yet again, musical creation on the highest level.

The Kontra Quartet’s pioneering recordings remain the only available competition for these quartets. As with the two previous instalments, however, I prefer the Nightingale’s slightly more nuanced approach. Compare the opening minutes of No 4, for example: beautifully paced and luminous in texture, the Kontras almost seem overbearing by comparison, though it did not seem so 30 years ago! The older recordings had a larger, more resonant acoustic: compare the Fourth’s Presto to hear the difference between the intimate (preferred in this repertoire) and the cavernous. Strongly recommended.