Completed in February 1928

At 06.01 hours on 3 Apr 1941, the unescorted Thirlby (Master Philip Edmund Birch), dispersed from convoy SC-26, was hit in the stern by a G7a stern torpedo from U-69 (Metzler) in 58°22N/28°55W. The Germans reported that the target sank immediately, however the ship which was en route from St. John, New Brunswick to Hull with a cargo of wheat did not sink and was later repaired. Two of 40 men on board were lost. Earlier that night, the Thirlby in station #12 of the convoy had probably been hit by a dud from U-46 (Endrass) and was on 10 April further damaged by a bomb from a German aircraft.

At 08.12 hours on 23 Jan 1942 the unescorted Thirlby (Master Philip Edmund Birch), a straggler from convoy SC-66, was hit by a stern torpedo from U-109 and sank by the stern after 10 minutes 12 miles 240° from Seal Island, Cape Sable. Three crew members were lost. The master, 31 crew members, nine gunners and the US pilot were picked up by the American steam merchant Belle Isle and landed at Halifax. The U-boat misidentified the victim as Greek steam merchant Andreas (6566 grt) by an intercepted radio message.