 Stanier, Chief Mechanical Engineer of the LMS, ordered the rebuilding of the unique experimental high pressure compound locomotive 6399 "Fury".The Schmidt-Henschel boiler was replaced with a tapered boiler, with a drumhead smokebox, designated type 2.The type 2 boiler had a tube surface of 1669 square feet, formed by tubes 2⅛ inches in diameter and 14' 3" long.