[5] From the age of 11, Williams attended summer courses with Andrés Segovia at the Accademia Musicale Chigiana in Siena, Italy.

He has extended the repertoire by commissioning guitar concertos from composers such as Peter Sculthorpe, Stephen Dodgson, André Previn, Patrick Gowers, Richard Harvey, and Steve Gray.

To encourage phrasing, tone production and all-around musicianship, Williams arranges for students to play together in ensembles, choosing works from the existing classical music repertoire, such as the "easier Haydn String Quartets".

The piece originally included only the first few bars of the tune as it is known today, but at Williams' request Myers rewrote and expanded it into the better-known guitar arrangement.

Between 1978 and 1984, Williams was a member of the instrumental fusion group Sky, with whom he recorded six successful albums and scored a UK Top Five single with "Toccata".

The duet featured on the resulting album and the film version of the show, bringing Williams to the broader attention of the rock audience.

Williams and his third wife, artist Kathy Panama (whom he married on New Year's Eve 2000),[10] reside in London (Hampstead) and Cornwall.