In October 1928 A.V. Roe, together with John Lord and Harry Broadsmith, resigned from A.V. Roe & Co.—lately taken over by Siddeley—receiving £42,500 for their shares. This they invested in S.E. Saunders Ltd (see Saunders), company being renamed Saunders-Roe Ltd. commonly abbreviated to Saro. With other investors this provided capital for switch to metal construction, initially with longitudinally ribbed (corrugated) hull obviating need for stringers, first with A.17 Cutty Sark monoplane amphibian and larger A.19 Cloud, A.21 Windhover and A.27 London biplane flying-boat (30 for RAF). A.33 (4 x Perseus) remained prototype, followed by S.36 Lerwick, with smooth stressed skin but a failure. East Cowes factory built 453 Walrus and all 290 Sea Otter amphibians, as well as wing of Short Shetland. Post-war work included SR.A/1 jet fighter flying-boat (July 1947), 3 SR.45 Princess large transport flying-boats (22 August 1952), SR.53 jet/rocket supersonic fighter (with de Havilland Spectre rocket engine and HTP auxiliary power system, DH having acquired interest in Saro in 1956) and Skeeter and P.531 helicopters (20 July 1958) developed at former Cierva works at Eastleigh. Saro also built SR.N1 (1959), world's first hovercraft, and had many subsidiaries, some going to de Havilland and main company to Westland 1959 which continued Skeeter and Black Knight rocket and developed P.531 into Scout/Wasp.