The Northern Barrage was being discussed in July 1939 but mine laying ships were not available at the time. The plan was to lay mines from Orkney, including Shetland , Faroe to Iceland. When Germany invaded Norway the plan was accelerated and five ships were requisitioned to be converted to minelayers.
In October 1940 a total of 10,300 mines were laid south of the Faroe Islands and by the end of 1942 92,083 mines had places in the Northern Barrage (35% of all British Mines), but the passage of U-Boats had not really been affected.
Mines were just not a problem for those at sea, they would break free and get washed a shore and cause problems to civilians and the forces alike.
I was talking to Gracie Laurenson , just before she passed away and she told me her brother was blown up by a mine washed ashore at Meal beach on Burra. He was trying to pull it to a safe area when it went off, the explosion was heard in Scalloway.
Storms from the west always had a `Banks alerts' so trying to collect drift wood was always going to be hazardous as mines we brought ashore as well.
Down at Sumburgh explosions could be heard on a regular basis, this was often down to the Construction teams but occasionally a mine would hit the rocks and there was bombings as well, the German dropped delayed action bombs which went off well after the Luftwaffe had left.
A short distance away a mine was literally thrown up among the rocks at Grutness but failed to explode. A team was deployed and the mine deactivated but left in position where it can still be seen today. It was in the 1950's that it was decided to set fire to it but even after years of rust it survives
Allen Ferguson Laurenson , Royal Navy Volunteer Reserve, Killed 24 November 1941 aged 38 at the Knab when a mine exploded
British mine washed up at Sandwick in Unst
Walter Jamieson was killed on the 24 January 1942. He was repairing damage caused by a mine explosion at the Sletts in Lerwick on the 23 January when another mine blew up
Photo Brian Duncan
This mine was moved next to the Fort Chippy before eventually disappearing