Franklin Mutual Advisers has written to Songbird Estates to indicate it plans to accept any cash offer for Canary Wharf Group shares from a Qatari-led group bidding for Songbird. News of the letter was given as the bidders for Songbird, Qatar Investment Authority and its bidding partner, U.S. investor Brookfield Property Partners, published the final offer document for their 2.6 billion pound bid for Songbird.