Scandinavian migration to the United Kingdom
Scandinavian migration to the British Isles is a phenomenon that has been occurring for nearly 1,500 years. Today, tens of millions of people living in the United Kingdom have some Scandinavian ancestry. Because of Nordic people's long history and presence in the UK, it is unknown how many Britons have Nordic ancestry.
A study into the Scandinavian ancestry of British people found that there is evidence of particular concentrations in Shetland and Orkney in Scotland, Isle of Man, Wirral, West Lancashire and Cumbria in England, Western Isles and Skye in Scotland, Mid-Cheshire in England, Western Scotland, and Anglesey in Wales.
Vikings and the Danelaw 
Scandinavian settlement in the UK began with the Viking invasions of the British Isles. These are thought to have begun with the sacking of the monastery at Lindisfarne off the Northumbrian coast as early as AD 793, followed by attacks on Jarrow (794) and the Columban church of Iona (976, 802, 806). Scandinavian Vikings soon dominated the sea routes and coastlines stretching from Norway to Shetland, Orkney, Mainland Scotland, the Hebrides and Ireland. The period of Scandinavian political and cultural domination in this region lasted until 1472 when Orkney and Shetland became part of Scotland. Scandinavian immigration had a greater impact on the more sparsely-populated areas of the British Isles, especially the Northern Isles and the Hebrides. Early in the 11th century the king of Denmark became king of England as well. And in 1066 there were separate invasions by the king of Norway, Harald Hardrada, and duke of Normandy, William the Conqueror, the latter the descendant of Scandinavian settlers in northern France.
The Danelaw was a name given to a part of the British Isles, now northern and eastern England, in which the laws of the Danes held sway over Anglo-Saxon tradition. Its origins lay in the Viking expansion of the 8th century, and a Scandinavia which saw the onset of a rise in productivity and the subsequent growth in populations. Its name is also used to describe the set of legal terms and definitions which were to be treatise between Alfred the Great and the Danish warlord Guthrum, which were put down following Guthrum's defeat at the Battle of Edington, in 878. Later, in 886, the Treaty of Alfred and Guthrum was created, founding the boundaries of their kingdoms, with provision for relations between the English and the Danes.
Although one must be cautious about assuming mass movements of people during the Viking period and assuming the Scandinavians were an actual race of people during these times. Dr Julian Richards, a prominent British Archaeologist and Historian in his book Viking Age England suggests the Danes never acted as an actual race of people within England. He also suggests there was nothing particularly Viking about York except for the possibly adoption of Scandinavian type brooches and deposits in York match those found in Durham. He goes onto explain that both Anglo-Saxon and Viking armies were quite small in the Dark Ages and considering recent Viking burial finds consisting of no more than 50-60 individuals, it would be wrong to assume mass movements of people.
Connections with Scandinavia have certainly been happening since the Neolithic as shown by Stephen Oppenheimer and others and it would be wrong to assume that either R1a or I1 necessarily only came with Anglo-Saxons or Vikings as Britain was connected to Northern Europe for thousands of years. Discoveries at Sutton Hoo and Beowulf show clear Scandinavian connections even before the Vikings arrived, in fact, Beowulf is set entirely in Scandinavia. Trade involving Amber from the Baltic also show connections across the North Sea during the Anglo-Saxon period. Place names have been seen as a major reason to believe in mass folk movements however it has been proposed that Germanic origin place names have been in Britain at least in Roman times (by the http://www.archaeology.ws and www.proto-english.org backs up this claim) as Vindolandia (vindr from the Old Norse and land from the Germanic) and many places can be explained by Old English elements even in Cumbria.
Thorpe was once considered Danish but now has been revised to Old English and as shown by Julian Richards many Scandinavian names could have simply been fashionable or popular amongst the English. One cannot therefore assume Danish or Norse place name elements come from the Vikings most places were found to have pre-Viking settlement underneath and one would expect with mass folk movements new settlements on virgin ground. Three place names found in Yorkshire (written by http://www.yorkshiredialect.com/Ambig.htm) with -by endings were found to have pre-Viking churches and no Scandinavian written inscriptions on the crosses which is odd considering a mass movement of people. Other sites urge on the air of caution (http://www.viking.no/e/england/danelaw/epl-danelaw.htm). Many Old English and Old Norse/Danish place names were identical and place name elements such as Kirk is found in numerous Germanic Languages including German Kirche, Dutch Kerk etc. Norse influence has been found in the North of England including wrist clasps from the 7th century found to be popular in Scandinavia. Indeed Julian Richards suggests terms such as Soakman may well be of great antiquity.
Therefore it is not necessary to presume that many elements that appear Scandinavian to actually come from the Vikings, with the ongoing trade and connections with Northern Europe especially from the Neolithic onwards many elements could come from sustained connections with North Europe. Given genetic evidence by Oppenheimer and others that suggest no evidence of mass movements and including the fact R1b is also found amongst Scandinavian populations it would be wrong to make any assumptions on the connections between Britain and Northern Europe. Given the fact little is known of place names or laws of the north and east of England during the Anglo-Saxon period and as suggested by the www.proto-english.org that a Scandinavian type of proto-English was spoken in the north in Roman times then many features associated with Vikings may actually be older. In deed, much of Anglo-Saxon England was written in Wessex from a southern English perspective and few documents in the north and east and midlands survive. However Julian Richards does suggest Old English was in the vernacular due to written inscriptions found in those regions.
See also 
- Excavating Past Population Structures by Surname-Based Sampling: The Genetic Legacy of the Vikings in Northwest England
- Goodacre, S; Helgason, A; Nicholson, J; Southam, L; Ferguson, L; Hickey, E; Vega, E; Stefánsson, K; Ward, R; Sykes, B (2005). "Genetic evidence for a family-based Scandinavian settlement of Shetland and Orkney during the Viking periods". Heredity 95 (2): 129–135. doi:10.1038/sj.hdy.6800661. PMID 15815712.
- "Gene geography: Do you have Viking ancestry in your DNA?". Wellcome Trust. 2004. Retrieved 9 January 2010.
- Branagan, Mark (30 January 2009). "'Time team' to seek out genetic secrets of Yorkshire's Viking past". Yorkshire Post. Retrieved 9 January 2010.