As built, they were powered by two Ruston-Paxman Deltic 9-59K diesel engines rated at 1,900 brake horsepower (1,400 kW) each, which drove two propeller shafts, giving a speed of 17 knots (31 km/h; 20 mph).

For minehunting, the ships would use Type 193M sonar to locate potential mines, which could then be investigated and if necessary destroyed by two PAP-104 remotely controlled submersibles or divers.

[3][4] She was the twelfth of the thirteen Hunt-class vessels, and was built as Yard No.4256 by Vosper Thorneycroft shipbuilders at Woolston, Southampton.

[1][5] Berkeley was commissioned on 14 January 1988,[4] and after sea trials, was assigned to the 1st Mine Countermeasures Squadron based at Rosyth, Scotland.

[6][7] On 27 October 2020, after sailing from Salamis Naval Base, HS Kallisto was severely damaged in a collision in the Saronic Gulf with the Portuguese-flagged container ship Maersk Launceston, which had just departed from the port of Piraeus.