I'm only half wy through Colin's book and this may get mentioned again further on but if he doesn't then he does not say that Sheila wrote 'i hate this place'. What he has said about it up to page 119 is only this:
"All of a sudden, Ann broke into out thoughts and came in. She said they had thought it better to put the room back the way Bambs had had it. Rather than leave it empty, after the twins' beds had been removed, they brought Bambs's old bed back in. 'Have you seen this?' asked Ann, pointing out some words scratched into what looked like new paint on the wardrobe door. 'I HATE THIS PLACE,' it said. I then remembered the police asking me about it, but on seeing those words I felt as if I had seen them before, in the last year or so - probably when I stayed at Christmas, although I couldn't be absolutely sure. I guess Bambs must have written it out of frustration on one of her earlier, more anguished visits. It seemed sad but now quite unimportant."
This could have been written at any time in the history of that wardrobe and by anybody that had been in that room. I don't want to incur the wrath of Patti but Colin says 'I guess' he may come back to this later but if not, this is far from conclusive. Patti, if I'm wrong then I'm happy to be told.
