Oh, to have been there! This recording from the 2016 Steinway Spirio Two Piano Festival at Pizza Express in London caught the last live encounter between two of the UK's finest improvising pianists, their first having been some 35 years before. Each has a solo piece on the album but the heavyweight item is an extended improvised duet, running in at just shy of 47 minutes. That said, it is fascinating to be reminded of their separate stylistic voices before hearing the different ways collaboration enlivened their imaginations. Keith Tippett's solo – 'Sea Walk' – has many of his hallmarks: Debussy-esque carefulness interrupted by sudden jazzy flourishes, layers of intense sonic texture and acoustic distortions, dynamic swells and rhythmic undertow, all shaped to a natural conclusion by his own logic.

There's a more obvious jazz language behind Howard Riley's 'Misteriously/Round Midnight', with Monk's timing and modes taken apart in evolving mutations towards an emphatically climactic finish.

Both solo pieces make for an excellent listen, naturally, but here they serve as a warm up act for something bigger than its parts – the duet 'Journal Four'. Starting with sudden staccato monotones, exercises in rhythm build to a rolling orchestral sound through a sequence of exploratory themes. What then follows has a unity of purpose that never flags as melodic and rhythmic ideas are passed to and fro, embracing a moment of township jive, a tidy little waltz Erik Satie might have conjured and finally the disjointed blues of Monk's 'Misterioso' taking it to a close. It feels perfectly crafted, as if two artists had covered a canvas together to produce one immaculate painting. As Riley diffidently observes in the liner notes, “It worked, that's all I can say” – and, indeed, that's all that needs saying.