According to the seller (who relisted the book):
I was given it by a friend who worked in a London bookshop. Sinead went through a phase a few years ago where she renounced all her worldly good and decided to get rid of, among other things, all her books.
As to why it bears those inscriptions-I was told Sinead was given the book by Shelley winters. As to why Linda lee Bukowski then signed it -I dont know.
but the signatures are genuine.