From all I have read, he was a quick spinner like O'Reilly, Verity and Underwood.
A 1963 tribute by John Arlott. Make of it what you will.
His usual pace was about that of Alec Bedser, with a faster ball and a slower one, in well-concealed reserve, and the ability to bowl a yorker. He himself is content that he was essentially a spin bowler, that his movement through the air was, in modern technical language, swerve - obtained by spin - rather than `swing', which derives from the 'seam-up' method. Certainly he made the ball move both ways through the air, and-with a first and second-finger application rather similar to that of Ramadhin - he bowled both the offbreak and the legbreak. Indeed, he could bowl the googly at about slow-medium pace and where, in exceptional conditions, the pitch dictated it, he could be a fine slow bowler.