I just listened to Marina Hyde and Richard Osman talking about this on The Rest is Entertainment (PRH is also RO’s publisher), and he reiterated that the contract that Sally Walker would have signed (or both of them, I suppose, if they’re in fact co-authors under the name Raynor Winn) would have put all legal responsibility for untruths in the memoir on them, not PRH. So the publisher will be dealing with reputational damage, sure, but bear no legal responsibility for untruths in the book. That’s on the Walkers.
RO said he could absolutely see why the publisher had bought it (I agree) and mentioned £30 k as a likely ballpark advance sum, Marina said she thought they wouldn’t have needed to pay that much, But Richard said he thought there could have been a bidding war for much more otherwise.
They both thought that the film production company would have been likely to do far more fact checking, as the money invested is far more. But clearly the Walkers passed whatever due diligence was done.
Neither had read it, though Marina has just bought it ;Richard pointed out that some of the cover price will still go to the Walkers) and Marina said she absolutely understood why readers who’d identified with the book felt so lied to.
She also specifically said Mumsnetters and Tattle Life people were particularly incensed.😀
ETA They also suggested that the original MS is likely to have skated much more lightly over the reason why they were homeless, but that an editor is likely to have said the reader needed more detail.