[1] Keston's best known acting performance may be his portrayal of Gehn, the complex villain from the video game Riven: The Sequel to Myst (1997).
(A short scene in which Keston is heard singing "O Sole Mio" is hidden in the game, in a type of file known as an Easter egg.
In 1968, John Keston appeared with Juliet Prowse in the original West End (London) production of Neil Simon's Sweet Charity at the Prince of Wales Theatre, in the role of Vittorio Vidal, receiving billing directly below the title.
Charity was his only West End credit; he had previously appeared in London productions of Sleeping Beauty, House of Cards, The Ideal Husband, Private Lives, and Billy.
In 1974, Keston travelled to Washington, D.C., with the Royal Shakespeare Company's touring production of Sherlock Holmes, directed by Frank Dunlop, with artistic director Trevor Nunn.
The full title of the play is Sherlock Holmes: Being a hitherto unpublished episode in the career of the great detective and showing his connection with the STRANGE CASE OF MISS FAULKNER.)
Keston relates autobiographical episodes of his early days as an actor, when he would dash to the theatre by train with just enough time to make up.
Then, in full view of the audience—and in almost no time—he puts on a dash of make-up, applies a wig and beard with spirit gum, and slips into a nightgown, to become the historian John Aubrey in his late life.
Poems, selections from Gerald Finzi's A Young Man's Exhortation, and other songs about the transition from youth to old age make up the act.
During his career there, he was the preferred vocal instructor for many talented and ambitious students, many of whom went on to become accepted into graduate programs at the country's most prestigious music conservatories.
He appeared as The Jester in annual Madrigal Dinners, presented by The Bemidji Choir and The Chamber Singers under the direction of choral conductor Paul Brandvik.
He wrote a thesis on composer Gerald Finzi, whose natural treatment of spoken cadence in his melodies appealed to Keston.
On 15 April 2005, Keston set a half-marathon M80 world record of 1:39:27, at the sixth annual Earth Day Half Marathon in St.
This is still the best time achieved by an 80-year-old, but was subsequently beaten as an M80 record by the Canadian runner Ed Whitlock, who ran 1:38:59 at the age of 81 in Milton, Ontario.