The photos from SW's IG feed (there's one of SW in Grant's meadow) and numerous snaps of the walk which have appeared alongside various articles, together with her assertion that they walked between 2 and 10 miles a day (depending on the weather, how they felt etc) based on notes written in pencil in the margins of the guidebook by Moth (perhaps subsequently reannotated in a second copy of Paddy Dillon's guide to the SWCP) I can largely accept.
What I find much more hard to believe is that somehow SW managed to transcribe verbatim many of the conversations and thoughts that she had at various stages during the walk as she wrote TSP some 2-3 years after the walk was completed. I suspect a hell of a lot of 'reimagining' has gone on and that a huge number of the incidents described in the book have been massively embellished.
So when you add this to the deliberate distortion of the origins of the house repossession and the CBD diagnosis in 2013, then in my book, TSP is, as the Observer claims, based on a web of fabrication,deceit, falsehoods and downright lies.