During World War II an anti-tank wall measuring high and wide and consisting of concrete blocks with a solid infill of concrete. Approximately 50% of the original wall still exists. Additional defences included barb wire along the harbour walls and cliffs. Certainly the focus of attention in Mullion Cove for the last 70 years has been damage caused to Mullion Harbour. During the Second World War the owners of the Harbour were engaged away from home, their main business connected to the repair of bomb damaged UK cities. With many of the fishermen away at war skilled stonemasons and other labour were also in short supply. Maintenance of the harbour proved difficult. This was also the case for other harbours and stone structures in Cornwall. By 1944 the small number of fishermen who remained were struggling yet again to make a living as the end of the south pier had begun to collapse into the harbour. Fishermen attempting to earn a living were refusing to pay their harbour dues. There were discussions about the problem at the Cornwall Sea Fisheries Committee meeting in March 1944 and there were attempts to involve the District Council. It was noted that if there was a desire to repair the harbour then a certificate would be required from the Ministry to the effect that it was worthwhile. In 1945 ownership of the harbour, Island and nearby coastal cliffs was handed over to the National Trust. The National Trust initially thought that repair was economically unjustifiable but on aesthetic grounds they felt duty bound to do so. In 1947 the west pier had become undermined and in danger of falling and the Trust launched an appeal for £2000 to safeguard the harbour. This began the post-war phase of rebuilding. Post War Development Plans provided for coastal communities to be able to live without damage to their amenities.