Set of adjoining concrete flax retting buildings to the immediate north of the former flax factory at Metheringham Heath Lane. The buildings were constructed during the Second World War, along with the majority of the factory complex. The structures housed large concrete tanks, used for the rettting of flax, a process by which de-seeded flax straw was steeped in water in order to rot the woody parts and allow the easier removal of fibres from the plant. Brick structures attached to the retting tanks would have housed pumping machinery that heated and pumped the water to the tanks, speeding up the retting process. After retting, the straw would be dried and stored prior to continuing their processing back in the main part of the factory (see PRN 65854). The retting tanks were demolished in 2015. {1}{2}