[2] According to Cowper, he wrote the book almost immediately after his novel Kuldesak was published successfully in 1970, and Twilight was "a more substantial work in every way".

His publishers rejected it, and despite his discouragement he started the novel Clone with the idea of satirising science-fiction people who did not like Twilight.

It begins in an apparently fictitious coastal town called Hampton and goes to other places such as Oxford and Geneva, ending at a farm in Lincolnshire.

It begins with a scene of his finding the Lincolnshire farm and continues with a long flashback told in chronological order up to that point.

While admiring the aurora it produces, the comprehensive-school English teacher Calvin Johnson meets one of his students, Margaret Hardy.

It transpires that the Zeta research project produced no viable babies, and most of the subjects were killed or suffered mental damage.

The children conceived just before the supernova, the "Twilight Generation", prove to be Zetas who share feelings and clairvoyant visions even more strongly than their elders.

After an arduous trip to Lincolnshire (where the snow is not quite yet melting in June), they find the farm in the possession of a teen-aged orphan, Elizabeth, and her cousin, Tony.

Spencer concludes that Calvin intentionally sacrificed his life, as he knew this action was the only one both old humanity and the Zetas and Briarians could accept.

[4] Stephen E. Andrews and Nick Rennison omitted it from their list of "100 must-read science-fiction novels", but in his foreword, Christopher Priest said that it or Cowper's Road to Corlay "ought to be" there.

"[6] The Oxford Companion to Twentieth-Century Literature in English called it "perhaps his best novel" and grouped it as "one of his elegiac science fiction portraits of a fragile England threatened by transcendental change".