Two years later, he published his second novel, "The Lay of Sir Tristram", a retelling of the Tristan and Iseult legend interjected with the narrator's own love story and his meditations on the legend's fluctuating influence and interpretation over time. Griffiths's most recent novel, "let me tell you" (2008), uses a constrained writing technique similar to those employed by the avant-garde Oulipo group. In "let me tell you", Ophelia tells her story in a first-person narrative devised by Griffiths using only the 481 word vocabulary given to her in Shakespeare's "Hamlet". Griffiths's first excursion as an opera librettist was "The Jewel Box" which used music from Mozart's unfinished operas "Lo sposo deluso" and "L'oca del Cairo" as well as several arias and ensembles that he had written for insertion into operas by other composers. The story-line is an imagined reconstruction of a pantomime in which Mozart and Aloysia Weber are said to have taken part in 1783. "The Jewel Box" premiered in 1991 in Nottingham performed by Opera North and conducted by Elgar Howarth. It was subsequently performed in the United States by Skylight Opera Theatre (1993), Wolf Trap Opera (1994), Chicago Opera Theater (1996), and New Jersey State Opera (1996). It was revived by Bampton Classical Opera in 2006 for the 250th anniversary of Mozart's birth. His second work of this type, "Aeneas in Hell", was set to songs and dance music from Purcell's theatre scores and was devised as a "prequel" to the composer's 1689 opera, "Dido and Aeneas". It premiered in 1995 at the University of Maryland's Ulrich Recital Hall conducted by Kenneth Slowik. Griffiths's libretto for Tan Dun's "Marco Polo" was his first for an opera by a living composer. In the late 1980s Tan Dun has been commissioned by the Edinburgh International Festival to compose an original opera. As he recounted in a 1997 interview: "Marco Polo" finally received its world premiere in 1996, not in Edinburgh as originally planned, but in Munich at the Munich Biennale. Although Griffiths's libretto was not directly related to or based on his novel, the first line of the opera, "I have not told one half of what I saw", was the novel's final statement.