1. A HANGER AND TOOL FOR USE IN SUSPENDING A STRING OF TUBING OR CASING IN A WELL STRUCTURE COMPRISING: A HANGER BODY HAVING AN AXIAL BORE AND AN EXTERIOR TAPERED SURFACE INTERMEDIATE ITS ENDS FOR ENGAGING A COMPLEMENTARY SURFACE IN THE WELL STRUCTURE; AT LEAST ONE LATERALLY MOVABLE LOCKING ELEMENT CARRIED BY SAID HANGER BODY FOR ENGAGEMENT WITH A RECESS WITHIN THE WELL STRUCTURE; FIRST THREAD MEANS ON THE UPPER INNER EXTREMITY OF SAID HANGER BODY; SECOND THREAD MEANS OF OPPOSITE ROTATION FROM SAID FIRST THREAD MEANS ON THE UPPER OUTER EXTREMITY OF SAID HANGER BODY; HANGER SLEEVE MEANS ENGAGING SAID SECOND THREAD MEANS AND INCLUDING MEANS ENGAGEABLE WITH SAID LOCKING ELEMENT TO MOVE THE SAME LATERALLY; A TOOL BODY HAVING A BORE COAXIAL WITH THE BORE OF SAID HANGER BODY; A TOOL SLEEVE CONNECTED TO SAID TOOL BODY FOR ROTATION THEREWITH AND FOR INDEPENDENT LONGITUDINAL MOVEMENT, THE LOWER END OF SAID TOOL SLEEVE THREADEDLY ENGAGING SAID FIRST THREAD MEANS; AND COMPLEMENTARY TOOTH AND SOCKET