Since some people here aren't familiar with Jonathan Powell, I've attached a brief biography (from
https://www.bmic.co.uk/) Apologies to Dr. Powell if this info is incorrect....

Seeing that he specializes in the works of Sorabji (among others), I guess it may be a good source for someone looking to get info on how to perform his works...
Jonathan Powell is a composer, pianist and writer on music. Self-taught as a composer, he first performed his works at the Brighton Festival and Dartington in 1989. Since then, he has received performances and commissions from leading exponents of new music including the London Sinfonietta, the Arditti Quartet, the Composers Ensemble, Jane Manning, Valdine Anderson as well as the pianists Stephen Gutman, Nicolas Hodges and Thomas Adès (at the first State of the Nation event in 1997). His works have been heard at the Aldeburgh, Almeida, Bath, Cheltenham and Huddersfield festivals, the South Bank Centre and the BBC Radio Theatre as well as in continental Europe, Japan, Australia and the US. Nearly all work completed since 1994 has been commissioned and most works have been broadcast or recorded. An hour-long programme devoted to his work (including several pieces he especially recorded for the event) was broadcast by BBC Radio during the summer of 2001. Three works – the Barcarolla for piano, Saturnine for ensemble and Sirenland for ensemble – will be recorded for commercial CDs during the year. His String Quartet No 2 was commissioned by the BBC and given its world premiere by the Arditti Quartet in June 2003.
As a pianist, he studied with Denis Matthews and Sulamita Aronovsky, making his début at the age of 20 at the Purcell Room. In 2000 he performed in Russia where he was acclaimed as a ’great virtuoso’ by the press. He is currently fulfilling a busy schedule of recordings and international concert appearances, specialising in the works of Scriabin, Szymanowski, Sorabji and others. He was awarded a doctorate from the University of Cambridge for a dissertation concerning Scriabin and his influence on Russian music; he has published major articles on Scriabin, Ciurlionis, Futurism and Soviet music.