and is relaxed, the dynamic level pp throughout as the music flows lyrically through gentle counterpoint.
Variation V, marked Molto allegro, is more dissonant and contrapuntal, built largely on triplet motives, and the tonality is more difficult to sense.
The texture rapidly changes for Variations X, XI, XII and XIII, all of which are each only twelve bars in length.
This slow movement then gives way to what may be termed a little scherzo, made up by Variations XVII, XVIII and XIX.
They give way to another slow movement that is made up by Variations XXX, XXXI, XXXII and the start of the fugue.
Each of these three variations gradually builds in emotion – XXX is mysterious and dark, XXXI appears to be moving towards greater light.
The Fuga, lasting approximately thirteen minutes, begins with a second violin solo, announcing a sad, lyrical subject that rises and falls gently.
It is then joined by the viola which plays the theme in inversion, giving the music a modal texture.
For several minutes the fugue progresses with a sorrowful mood, flowing with gentle counterpoint, before building to a climax.
The composer and musicologist Lionel Pike described it as a "remarkable tour de force...[Simpson] has explored thoroughly every facet of Haydn's theme in a way which for fertile imagination, invention, and contrapuntal skill challenges comparison with the variations J S Bach wrote for Goldberg to play to the insomniac Count Kayserling.
Brown commented that "Simpson's ideas are so characterful that their reverses almost always are not only fascinating in themselves but throw more and different light on the original forms.