s 41 What evidence to be given when statement forms part of conversation, document, book or series of letters or papers
41. When any statement of which evidence is given forms part of a longer statement or of a conversation, or part of an isolated document or is contained in a document which forms part of a book or of a connected series of letters or papers, evidence is to be given of so much and no more of the statement, conversation, document, book or series of letters or papers as the court considers necessary in that particular case to the full understanding of the nature and effect of the statement and of the circumstances under which it was made.