Stack Rock Fort off the cost of Pembrokeshire, Wales is a 19thC 3-gun fort which was disarmed in 1929 and went through a variety of owners and uses before being donated to the nation in 2005. CADW, the Welsh Heritage office started a program of consolidation and repair in 2006 and this was ongoing when the Great Panic started. The Fort became home to a survivor community, largely made up of the workers who had been there at the collapse and their families.
Only accessible by water the Fort was able to see off zombie and raiders both. It would only reluctantly surrender to the UK government during the clean up of the Isle, and many would not step foot on the mainland even for years afterward, preferring their Fort life.