The De Havilland Venom was a fighter-bomber designed as a replacement for the Vampire. Whilst it shared the general appearance of the Vampire externally, many of the internal components were a total redesign. The prototype Venom first flew in 1949. The design was navalized in 1951 as the Sea Venom and served with distinction in the Royal Navy. The Sea Venom also served in the Royal Australian Navy and the French Navy, licensed-built. In total, more than 1,480 Venoms and Sea Venoms were built, with some serving into the 1980's with the Swiss Air Force. The Mk.21 was a further refinement of the Sea Venom, with the Rolls-Royce Ghost 104 turbojet, clear-view canopy, and new radar equipment. The Mk.53 is the Australian designation for the Sea Venom and is very similar to the Mk.21 configuration.