The Blackstone Group Inc. (NYSE:BX) is said to be in exclusive talks to invest about £900 million in Bourne Leisure Holdings Limited. Talks are continuing but not thought to be at an advanced stage, meaning a deal may not be announced imminently, according to a source close to the negotiations. The Cook, Harris and Allen families would retain a significant stake in the business following a sale. The Times first reported the negotiations. Bourne Leisure and Blackstone declined to comment.