Herring Gulls breed in an area extending from Iceland and the Faeroes to northern Fenno-Scandia and the White Sea, with further populations in Siberia and North America.
In Britain they breed all around the coasts and also increasingly inland since the mid 20th century, often in mixed colonies with Lesser Black-backed Gulls in industrial and urban sites. Non-breeding birds in summer can be found widely throughout most parts of the country apart from the higher uplands. In winter, the mainly sedentary British population is joined by birds moving south from Fenno-Scandia and the Baltic. Though the main concentrations remain near the coasts, they can, as in summer, be found in most areas apart from the highlands.
In Wiltshire prior to the mid 20th century Herring Gulls were mostly recorded in over-flying flocks in winter or on passage in spring or autumn. After the 1939-45 War there were reports of them foraging on rubbish tips or roosting at the Cotswold Water Park. The first few records in Britain of gulls nesting on buildings occurred in Devon and Cornwall before the war; then after the war the numbers of known colonies increased from 14 in the 1940s to 55 in 1970. The first record of breeding in Wiltshire occurred when two nests were found on a factory in Trowbridge in 1995, which featured as the only confirmed breeding record in Birds of Wiltshire. However a specially commissioned survey of roof-nesting gulls in Wiltshire in 2003-04 found them nesting on roofs in seven different towns, with a total of 97 pairs and 43 confirmed nests. It was conjectured from these figures that there were likely to have been more nesting birds present during the Birds of Wiltshire surveys than had been noted - possibly somewhere between 25 and 50 pairs. WTA2 recorded confirmed or possible breeding in 15 tetrads.

The following references are used throughout these species accounts, in the abbreviated form given in quotation marks:
1968-72 Breeding Atlas” – Sharrack, J.T.R. 1976:  The Atlas of Breeding Birds in Britain and Ireland. T. & A. Poyser
1981-84 Winter Atlas” – Lack, P.C. 1986:  The Atlas of Wintering Birds in Britain and Ireland. T. & A. Poyser
1988-91 Breeding Atlas” – Gibbons, D.W., Reid, J.B. & Chapman, R.A. 1993: The New Atlas of Breeding Birds in Britain and Ireland 1988-91. T. & A. Poyser
Birds of Wiltshire” – Ferguson-Lees, I.J. et al. 2007 : Birds of Wiltshire, published by the tetrad atlas group of the Wiltshire Ornithological Society after mapping fieldwork 1995-2000. Wiltshire Ornithological Society.
Bird Atlas 2007-2011” – Balmer, D.E., Gillings, S., Caffrey, B.J., Swann, R.L., Downie, I.S. and Fuller, R.J. 2013: Bird Atlas 2007-2011: the Breeding and Wintering Birds of Britain and Ireland
WTA2” – ("Wiltshire Tetrad Atlas 2 ") the present electronic publication, bringing together the Wiltshire data from “Birds of Wiltshire” and “Bird Atlas 2007-11”, together with data from further fieldwork carried out in 2011 and 2012.
"Hobby" - the annual bird report of the Wiltshire Ornithological Society.