High Quality Content by WIKIPEDIA articles! HMS Surprise (K346) was a Bay-class anti-aircraft frigate of the British Royal Navy. In commission from 1946 to 1965, she served in the Mediterranean Fleet as a Despatch Vessel for the Commander-in-Chief. Although principally employed for the use as a yacht by the CinC, Surprise was also deployed in its operational role as an anti-aircraft frigate. The archaic term "Despatch Vessel" was replaced by "Flag Frigate" in 1961.