Sentence:  raising his eyebrows, and looking slowly round him, 'I suppose I may speak the truth freely, as I know well enough that all to whom my vaticinations would be unwelcome are sure to mistake me for a <WSD>Cassandra</WSD>.' 
Meaning of the word marked with <WSD> tags:  A person who makes dire predictions, especially those which are not believed but which turn out to be true.