I quickly drink my late morning coffee and abandon the press pod, filled with newspapers featuring unflattering photographs of Kenny MacAskill. In Charlotte Square, the sun is blinding; the patio outside the London Review of Books tent is a blur of sunglasses, overpriced white wine and linen in varying shades of beige.

Sarah Waters draws a lively, diverse crowd, who are not wearing beige - and are clearly the sort of fans who not only read her books, but mark the arrival of a new Waters novel on their calendars in red pen and read it within a week. I overhear several people dissecting the plot of The Little Stranger as the lights dim.

Waters and chair Lesley McDowell, accompanied by a BSL translator, begin with a Q&A session which is rather like eavesdropping on two people having a rapid-fire conversation in a cafe. Waters describes The Little Stranger and her work in general in a refreshingly honest and professional manner, while maintaining a personable rapport with the chair and audience.

The story is set in post-WWII England, in a crumbling country house. “Everyone in that house could be described as a stranger”, Waters tells us. The author lists diverse sources of inspiration for her work: a conservative 1948 novel reflecting middle class fears of increasing influence from working class people, a contemporary Swedish horror film set in a council estate. The author describes the Gothic landscape as the underside of the realist novel - the nightmarish, sordid side of life depicted without romance.

Waters researched poltergeists and spooky houses for her new novel, loosely termed a ghost story. She describes the universals of poltergeist stories, which usually took place in an atmosphere of domestic unease and repressed fury. The concept of a poltergeist as a bundle of often female, often adolescent energy born out of extremes of emotion caused Waters to question whether we could all give birth to our own poltergeist, under the right circumstances. This is reflected to some extent in the title; "the little stranger" is a Victorian term to describe an unborn child.

Waters relied largely on diaries from the post-war period to set the tone, which recorded changing bureaucracy and the minutiae of daily life. Waters wrote The Little Stranger following The Night Watch, and for both novels was concerned with the post-war social landscape in the UK - including fears of men returning en masse from war having been trained in aggression, the changing interpretation of gender roles, and the changing significance of the class system. In many ways, says Waters, this was a good time to be a woman, to be working class, to be gay; opportunities for most of the formerly marginalised groups were increasing.

As we emerge from the RBS Main Theatre, a teacher is attempting to organise a large group of schoolchildren into tidy rows, with limited success. I sometimes forget that there's a robust yet less publicised set of events for children here.