The Laforey class were improved and faster versions of the preceding .[1] They displaced 965-. The ships had an overall length of 268feet, a beam of 27feet and a draught of 10feet. Lassoo was powered by two Parsons direct-drive steam turbines, each driving one propeller shaft, using steam provided by four Yarrow boilers.[2] The turbines developed a total of 24500shp and gave a maximum speed of 29kn. The ships carried a maximum of 280LT of fuel oil that gave them a range of 1750nmi at . The ships' complement was 74 officers and ratings.[3]
The ships were armed with three single QF 4adj=onNaNadj=on Mark IV guns and two QF 1.5-pounder (37 mm) anti-aircraft guns. These latter guns were later replaced by a pair of QF 2-pounder (40 mm) "pom-pom" anti-aircraft guns. The ships were also fitted with two above-water twin mounts for 21inches torpedoes.[3]
She was built during the First World War as part of an emergency program of naval construction, to an Admiralty design by William Beardmore & Company, Dalmuir. She was originally to have been named Magic but she was renamed Lassoo on 15 February 1915 before being launched on 24 August 1915. She was sunk by the German U-boat on 13 August 1916 off the Maas lightship in the North Sea.