Elizabeth Maconchy (1907-1994) was a pupil of Ralph Vaughan Williams and wrote in all genres, but it is especially her fine series of thirteen string quartets, which span the years 1932 to 1984, that is regarded as the peak of her musical achievements - they have been called as fine as those by Bartók and Shostakovich. For her biographical note, see my article in the series "Best String Quartets, Part 3 (1926-1945)."
[Elizabeth Maconchy]
Unfortunately, today Maconchy's music is severely and shamefully under-represented on CD and streaming. I have selected her one-movement Third String Quartet from 1938. As I wrote in my previous article: "There is a sturdy string sound, with especially powerful lower strings (Maconchy herself was a viola player). The music is slow and questioning, followed by an aggressive, rhythmic faster section, before again returning to the opening. Maconchy's compelling and original music has been said to be one of "impassioned argument" and that is also very true of this Third Quartet." It is here played by the PuraCorda Ensemble.
P.S. Also see this interesting article "‘The Impassioned Pursuit Of An Idea’: Elizabeth Maconchy And The String Quartet" on the musical blog Corymbus by Simon Brackenborough.
Also the First Quartet, completed in 1933 when Maconchy was twenty-six, is available via Youtube - note that even in this early work the sound world is already quintessential Maconchy. It is here played by the Bloomsbury Quartet.