I work at a large manufacturing site in northeast England, where several older production areas have been enclosed over time, and provide ideal nesting sites for Barn Swallows Hirundo rustica. In some cases, hygiene protection measures such as rapid-rise doors and bird netting have been installed to deter nesting birds. The Swallows have proved adept at overcoming these devices, however, and in summer 2018, I was working in a unit where about five pairs of Swallows were nesting, despite the deterrent measures in place (plate 221).