The novelist Vikram Seth is in delicate negotiations with his publisher Penguin over a $1.7m (£1.1m) advance for the sequel to A Suitable Boy after failing to deliver the manuscript on time.

Penguin UK bought world English language rights (excluding US) to A Suitable Girl, and set a deadline of June 2013 in the hope of publishing in the autumn to coincide with the 20th anniversary of A Suitable Boy's original publication. The publishing package on which the advance was staked included the new novel and a reissue of the paperback edition of A Suitable Boy, for which Penguin acquired rights from original publisher Orion.

However Seth's muse is not dancing to the publisher's marketing beat, and his agent David Godwin is fighting to keep the deal on track, acknowledging that the crucial 20th anniversary date has been missed.

Penguin's acquiring editors could have picked up clues from Seth's earlier work that he might have trouble hitting his deadline. A Guardian profile in 1999 pointed out that the character Amit Chatterji in A Suitable Boy is a loose self-portrait. "He mocks himself … for sitting about all day staring out of the window."

It continued: "The first section of A Suitable Boy, beginning with the wedding of the older sister of Lata, whose search for a husband is the heart of the book, was written quite quickly. But then Seth found himself blocked and, realising he did not know enough about India in the 1950s, concentrated on research for a year."

Seth described his own internal conflicts: "There have been dark periods, when I've felt hopeless in love, when I haven't been able to see a way out of a situation. Metaphysical struggles, if you like. At times I was acutely incapable of doing anything."

A Suitable Boy is a big act to follow: at 1,349 pages it is one of the longest books ever published in English. Set in India just after the country gained independence, the novel follows the story of four families over 18 months, as a mother searches for a suitable boy to marry her daughter. Although the book became a huge bestseller and was critically acclaimed, it was famously snubbed for the Booker Prize shortlist, prompting its publisher Anthony Cheetham to call the Booker judges "a bunch of wankers".

A Suitable Girl is expected to move the action from 1950s India to the present day, where we catch up with heroine Lata, now as a grandmother matchmaking for her grandson.

Observer writer Robert McCrum, who published Seth's 1986 novel The Golden Gate at Faber, said: "Ever since The Golden Gate, Vikram is a true artist who has always wrestled with words and meanings. In my experience of not publishing A Suitable Boy [McCrum was offered the book but turned it down], watching it mature into the huge bestseller it eventually became, Vikram is a writer who will always give his work another polish. He's slow, painstaking, but really good. The kind of novelist who's worth the wait."

Penguin is gaining a reputation for taking a hard-nosed attitude toward writers who fail to deliver. Last September the Guardian reported that it was suing 12 authors in a New York court over late or nonexistent manuscripts. They included Prozac Nation writer Elizabeth Wurtzel and New Yorker writer Rebecca Mead.

A Suitable Boy is one of the few literary novels from recent decades to have reached a mass readership: It was dramatised for radio in 2002, though a promised film version failed to materialise. More recently, a call by Guardianwitness for incongruous book covers, elicited this unusual interpretation of A Suitable Boy from one fan.