Keith studied at the Royal College of Music with Ralph Downes, Bernard Roberts and Ruth Gipps. It was at this time that Keith became inspired by the music and playing of Jean Guillou, who invited him to the Alpine village of L'Alpe d'Huez for one of the famous Guillou masterclasses. This led to Keith's life-long relationship with Guillou's music, and had a profound influence on his style of playing and approach to the organ. Keith soon discovered that one could play anything on the 'big little organ' of L'Alpe d'Huez in exactly the same way that, in the hands of the artist, the same is true of the masterpiece that is the organ of Gloucester Cathedral.

Keith John is renowned for his phenomenal technique and his imaginative use of the full range of colours from every instrument featured in his recordings and recitals. His transcriptions are regularly performed and have all been recorded, winning critical acclaim. His composition Rhythmic Energy has become a tour de force in many organists' recital repertoire.

Keith's recordings have won Editor's Choice in both Organists' Review and Cathedral Music, and have been well received in publications such as Gramophone, the London Sunday Times and the BBC Music Magazine.