 She arrived back in Portsmouth on 21 February 1946, and was reduced to Reserve status prior to conversion to Submarine Depot Ship, in which role she spent a lot of time at Rothesay.In 1953 she took part in the Fleet Review to celebrate the Coronation of Queen Elizabeth II.In October 1954 HMS "Montclare" was decommissioned, being replaced as the 3rd Submarine Flotilla depot ship by and laid up on the Gare Loch and then at Portsmouth.