On 5 January 1970, "Matapan" was towed to Portsmouth where she began her conversion, that resulted in her appearance becoming radically different from when she was launched in 1945. To house the x arrays required on either side of the keel, required the addition of a deep skeg on the bottom of her hull, which would increase her draught to and increase her displacement to 3835 tons. Additionally, a large bulbous sonar dome was added to her bow. All of her armament was removed and a new deckhouse and bridge were added forward, along with a plated foremast to house additional radars. Towards the stern, she was fitted with a second funnel to vent the exhaust gases from the generators needed to power the sonar, and a helicopter flight deck on a deckhouse aft. The ship was also re-wired and fitted with new operations and control rooms, and additional accommodation for scientific staff. The reconstruction work was completed in July 1972 and she began her sea trials.