SH4460 : A wartime remnantBelieved to be one of the concrete filled oil drums that acted as tying up points for landing craft involved in Operation Sandcastle of the mid-1950s. This was the postwar operation to dispose of the German chemical weapons stored at RAF Llandwrog that had reached a critical stage in their limited shelf life. The operation to dispose of them included building a new concrete slipway and assembly area opposite Fort Belan Dock. Landing craft were able to tie up there and to be loaded with the bombs that were then transported up to Scotland where they were transferred to a number of obsolete ships. These old merchantmen were sailed out to the north west of Ireland by RN personnel where they were scuttled.
Source: "Defending Anglesey" by Mark Dalton ISBN 978-0-9564405-8-7