The magazine's serious approach to rock music and culture, under the editorship of Ray Coleman, secured MM a huge circulation by the close of the 1960s and the start of the 1970s.
For two years, he signed and developed artists including Pete Wingfield, Stone Delight, Bryn Haworth and John Cale.
His music journalism has been gathered in the volume Long Distance Call: Writings on Music and biographies of Bob Dylan (A Man Called Alias), Miles Davis (The Man in the Green Shirt), and Phil Spector (Out of His Head) are among his list of other publications.
He has written several books on Formula One, including The Death of Ayrton Senna, Racers (an analysis of the main participants of the 1996 F1 season), Enzo Ferrari: A Life, and The Last Road Race (a study of the changing balance in Formula One between British and Italian teams, using the 1957 Pescara Grand Prix as the backdrop).
Williams' comments about music and related film, photography and art topics are published in the form of his blog, The Blue Moment.