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.