URBAN IMPACT. “In contrast, a gradual decline in urban centres continued, with little change for 50 years from the 1930s, before the urban population went into free-fall in the late 1980s or early 1990s. A gradual and continuing decline is probably also taking place in suburbs and small towns, though it has not yet become catastrophic.”
https://www.britishbirds.co.uk/wp-content/uploads/article_files/V96/V96_N09/V96_N09_P439_446_A004.pdf