Whilst a copious literature testifies to the value of subfossil insect analyses in the interpretation of Holocene deposits (Buckland Ind Coope, 1991; Elias, 1994), most of this results from studies of Coleopterous material . Although Dipterous fragments are often abundant in the same deposits, they have received little attention. This Thesis is concerned primarily with establishing the great value of Dipterous subfossill and the potential for advances in this field. Dipterous morphology is considered and features of primary value in the identification of subfossil material is highlighted. Problems with the traditional taxonolic criteria, insofar as identification of such material is concerned, are discussed, and new approaches are recommended. Thus, a brief survey of the morphology of Tipuloid larval head-capsules, and a revisional paper on the puparia of British Sphaeroceridlt, are included. The study includes many case-studies from excavations across the region, spanning the last 5,000 years. Although there, is an inevitable bias in favour of archaeological sites, and hence of the more synanthropic elements of the Dipterous fauna, situations un associated with human settlements are also discussed. A major objective in this work was to examine the role of Diptera in the insect colonisation of lands left in a state of tabula rasa by receding glaciations, The geographical aea concerned here comprises the entire North Atlantic continental seaboard and islands from France and Labrador northwards. This area saw the major western expansion of the Celts, Romans and the Vikings, from whose settlements much of the Dipterous material from archaeological deposits was obtained for this thesis. It also saw the eastern migration of Inuit cultures from the Canadian Arctic into Greenland. Dipterous subfossils tell us much of the living conditions and economies of these peoples.