Kay's career suggests a capable, slightly indifferent man who was content to have a steady gig and didn't feel he had to worry too much about the sort of music he was playing. He was doing paying gigs already by 1939 and in the 40s and early 50s he played with everybody from Miles Davis and Cat Anderson to The Clovers, Stan Getz and LaVern Baker. In 1955 he took over from Kenny Clarke in the Modern Jazz Quartet, and with that he had found his steady gig: he was with them until the 1974 annulment, and then rejoined when they restarted in 1981. In the interim he was as catholic as ever in his choice of work, even taking on the job of house drummer in the last years of Eddie Condon's club. John Lewis rarely gave him a feature in the MJQ, but only because Kay didn't seem to like them much: Sacha's March was his only regular solo in their later years. Despite suffering a stroke, he played his final gig with the band in the month before he died.

Biography from Richard Cook's Jazz Encyclopedia (2005).

If you'd like more information, check out The New Grove Dictionary of Jazz (2002) or The Biographical Encyclopedia of Jazz (2007), both of which are still in print.