David should use Form K015 for an application for an official search in the Land Charges Register. This form is used to request a search to reveal any entries that may affect unregistered land. Such searches are essential to ensure that there are no existing charges or restrictions that could impact the purchase. Key Point: Form K015 is used for an official search in the Land Charges Register, which is necessary for checking entries affecting unregistered land before proceeding with a purchase.