Originally Posted by fitz

Type 82 was originally intended as a follow-on to the Leander, to be built in similar numbers. Problem is, Type 82 cost 3 times as much as a Leander. No government was going to be buying those by the score. The final nail in the coffin was the death of the carrier program, whose existance justified the Type 82's in the first place.

Sea Dart was concieved from the beginning to fit in a frigate (Leander) hull which meant it was possible to build a frigate-sized Sea Dart ship in Leander quantities in order to get enough Sea Dart systems to sea to meet requirements. At one time it was thought as many as 25 Type 42's would be built. The Falkland's war effectively ended Type 42 orders.

Type 42 is really the minimum Sea Dart ship but they cut corners even then. The most obvious was the artificial restriction on length, introduced probably to keep the designers from adding equipment (cost) but much to the detriment of seakeeping, endurance, speed, habitability and future growth. At least the ships got 2 Type 909's. For a while they were only going to get 1.