As I've said before, there are only four of Tippett's works that I really like, all from his brief, early and 'lyrical' period - but these I like a lot! The others are A Child of our Time, the Corelli Fantasia and The Midsummer Marriage - and the Double String concerto (1938-9) is the first of this quartet that he composed.
It is quite readily enjoyable even on the first hearing - especially the sumptuous slow movement; being in the English tradition of pastoral music that links back to Elgar, Vaughan Williams, Butterworth and the like.
But it is immediately obvious that Tippett's music is distinctive in being highly contrapuntal; with a tremendous busyness of entwining independent lines in all the voices. There is also a lot of syncopation - which is something I particularly appreciate. The impression is one of great fertility of both imagination and sheer energy.
Once begun, the movements seldom 'settle' until they have finished - even the soaring and unwinding long melody of the slow movement is underpinned by counter-melodic activity in the lower voices, which keeps the harmonies 'off balance' until the final resolution.
I first heard this more than forty years ago as the flip-side of Vaughan Williams's Tallis fantasy; but I have been listening to it more frequently than ever before over the past several weeks, and just finding it more and more to my liking.
For me the concerto starts well, then keeps getting better and better - until the very end. The final movement combines the contrapuntal energy of the first with the lyrical melodiousness of the second in a completely satisfying way.