I will use this topic to present the history of British designed Sloops pre WWII, to the wartime frigates that evolved out of those designs. Being arbitary in my selection I'm beginning with what I personally consider the most elegant of the type, the RAN later River class, which were based upon the Bay class in RN service. Next will be the less lovely Diamentina, the last surviving (in service) of these ships; then, its back to the beginnings to show the interwar Sloops.