On 15 January 1902, the ceremony of placing in position the first foundation block and setting the tablet stone to commemorate the Naval Dockyard Extension scheme was held. See here
Mrs Powell, wife of the Commodore laid the foundation stone. The stone was placed in the seawall, west of the dock entrance. Current coins of the realm, a plan of the naval dockyard extension, local newspapers etc were inserted into a cavity in the stone.
I think the memorabilia from 1902 can be found in the Museum of Coastal Defence as mentioned here