The s were two classes of sixteen destroyers of the Royal Navy launched in 1942–1943. They were constructed in two flotillas, each with names beginning with "U-" or "V-" (although there was a return to the pre-war practice of naming the designated flotilla leader after a famous naval figure from history to honour the lost ships "Grenville" and "Hardy"). The flotillas constituted the 7th Emergency Flotilla and 8th Emergency Flotilla, built under the War Emergency Programme. These ships used the Fuze Keeping Clock HA Fire Control Computer.