used mainly traditional methods with as much welding as possible. Scantling was based on the Flower, but lightened in some areas. The wireless office (the same as on the Loch), the radar office, and the lattice mast were installed as prefabricated units. The Castle was armed with a Squid anti-submarine mortar, directed by Type 145 and 147B ASDIC. The Flower used the older Hedgehog mortar and could not be fitted with Squid. The first operational Type 147 and Squid were installed aboard HMS Hadleigh Castle in September 1943. In place of the BL 4-inch Mk IX main gun, the Castles had the new QF 4-inch Mk XIX gun on a High-Angle/Low-Angle mounting which could be used against aircraft as well as surface targets such as submarines. In service The Castle was criticized for being barely fast enough to fight German Type VII submarines and difficult to handle at low speed. Ships Royal Canadian Navy The following vessels were all originally built for the Royal Navy, but were transferred to the RCN on completion (for details of builders and construction dates see under Royal Navy below). All their pennant numbers (except Hedingham Castle, which was never completed), as well as their names, were changed when transferred. HMCS Arnprior (K494) (ex-) HMCS Bowmanville (K493) (ex-), sold to Republic of China as cargo ship, but taken over by the Communist People's Liberation Army Navy after the end of the Chinese Civil War and rearmed with Soviet guns, entering PLAN service as Guangzhou. HMCS Copper Cliff (K495) (ex-) HMCS Hespeler (K489) (ex-) (later SS Chilcotin) HMCS Humberstone (K497) (ex-) HMCS Huntsville (K499) (ex-) HMCS Kincardine (K490) (ex-) HMCS Leaside (K492) (ex-, later SS Coquitlam II) HMCS Orangeville (K491) (ex-), sold to Republic of China as cargo ship, but taken over by the ROC Navy on 29 June 1950 and rearmed with US guns, entering ROCN service as De An (德安) HMCS Petrolia (K498) (ex-) HMCS St. Thomas (K488) (ex-, later SS Camosun III) HMCS Tillsonburg (K496) (ex-), sold to Republic of China as cargo ship, but taken over by ROCN on 29 June 1950 and rearmed with US guns, entering ROCN service as Kao An (高安) Royal Navy The first of the Castle-class were the prototypes Hadleigh Castle and Kenilworth Castle, ordered on 9 December 1942; another 12 vessels were also ordered on 9 December, also under the 1942 War Programme. The remaining eighty-one