Of the eleven ships of the class ten were built in shipyards in northern England and Scotland, while the eleventh was built in Sydney, Australia.[2][3] One ship, HMS Bayonet, was lost when it struck a mine in the Firth of Forth on 21 December 1939, initially attributed to being laid by the U-21 on 4 November.[4] The second court-martial of HMS Bayonet's skipper found that the mine was part of a British defensive field laid by HMS Plover the day before[5]
