At this point I'd like to address the commonly received idea that Garson's piano work is more or less akin to that of Cecil Taylor.
Among pianists I would suggest he is closer (closest?) to Thelonious Monk, but there are major differences too. Monk's music was so much his own that he could not be an accompanist, and his music had much more to do with silence than Garson's does. To a certain extent Garson might be to Taylor what Coltrane was to Ornette Coleman.
Taylor's playing is mostly atonal, while Garson's, I feel, most of the time starts from a definite key, melody and rhythm and then subverts and twists them to change them into something completely different, in a way that feels perfectly logical. There are no gaps or leaps in his playing. You can hear he is transforming a tune from within, not taking foreign elements into it.
I lack the musical training to describe this more precisely but I can hear it for instance in the studio versions of Aladdin Sane and I'm Deranged, also in the version of A Small Plot of Land Adam has just given us - and eternal thanks to him for it.
I think this is why there is such a strong connection between Bowie and Garson: transforming his music and himself without solution of continuity is what Bowie achieved in the 1970s.
Wear your wound with honour.