He has already performed two complete cycles of the 32 Piano Sonatas, one in Perth and another in Greyfriars Kirk. Intriguingly, I've seen a reference to a possible cycle in Glasgow.
But here is something special. Last year Williams, a startlingly original and profound interpreter of Beethoven's Sonatas, visited the East Neuk Festival where he played two of the late Sonatas, the opus 109 in E major and the opus 110 in A flat major, both of which were recorded in Crail Church. The performances, beautifully captured, are as revealing as they are probing, with measured, well-paced playing, total structural command and infinitely nuanced expressivity which, in the heart-stopping variations of opus 109, reveals the maturity of Williams's thinking.
You can't get this in the shops. It's available at www.eastneukfestival.com. Essential for followers of this amazing pianist and devotees of these glorious Sonatas.