These were the first post WW11 ships, designed around 1950, for an A.S.W. role, and their hull shape and flared bow meant they could keep up a high speed chase in quite rough conditions.
The Admiralty's designers had, by now, recognized that the majority of existing ex WW11 A.S.W. Escorts and Frigates were, by then, more or less obsolete.
This was down to the tremendous advances in both capability and performance as had been demonstrated by the German "type XX1 u-boat".
This submarine was faster underwater, at around 17 knots, than many of its existing surface opponents.
It was also, at speeds of less than 5 knots, virtually silent with a submerged endurance of more than 72 hours.
It had an automated hydraulic torpedo re-loading system that could bring its tubes back into operation in minutes,
and, by now, the problems the Germans had previously had with erratic running torpedoes had been beaten.
Once the war had ended, thankfully before these formidable submarines became fully operational with the "Kreigsmarine",
the lessons learnt from captured examples of these boats formed the basis of nearly every nations modern "Submarine Fleet",
the end result in the RN being the superlative "O" Boats from the 60's and 70's.
It was this type of submarine coming into, chiefly the "Soviet Navies North Atlantic Fleet", that prompted the birth of this type of Frigate.
section updated Early August 2015. - ( # ) against name indicates new or updated photo's.