A few years ago, a story came out about 51 headless Vikings unearthed at a site in Weymouth, England. http://www.cnn.com/2010/TECH/science/03/12/viking.olympics/index.html
“On Friday, officials revealed that analysis of the men’s teeth shows they were Vikings, executed with sharp blows to the head around a thousand years ago. They were killed during the Dark Ages, when Vikings frequently invaded the region.”
Researchers have dated the remaines to the period between 890 and 1030 AD, postulating that it was a raiding party that was executed once it was caught too far from its boats.
During this period, the Anglo-Saxon kingdoms were well established in England. Weymouth would have been in Wessex, one of the primary and most powerful kingdoms at the time. http://www.dailymail.co.uk/sciencetech/article-1257333/Decapitated-Viking-skeletons-Weymouth-ditch.html
Kings of the period include Alfred the Great (871-899), Edward (899-924), and Aethelstan, credited with being the first King of England.
The Anglo-Saxons themselves had a long history of raids, which is how they settled in Britain in the first place. Britain was relatively free of raids from 600-800 AD, once the Anglo-Saxons conquered all but Wales and portions of Scotland. A new wave of Vikings (from Sweden, Norway, and Denmark) began with the raiding of Lindisfarne, England in 793 AD, however, and continued up until the Norman conquest in 1066. http://www.thenagain.info/webchron/WestEurope/VikingRaids.html
One of the reasons that King Harold Godwinson lost to William the Norman was because he’d had to fight off an invasion by Harald Hardrada (Norway) at the Battle of Stamford Bridge in late September, and then had to march his exhausted men to Hastings to face William, who’d landed unopposed on September 28.
It is important to note that the Normans (or ‘Northmen’) were also Vikings–just ones that had settled for a generation or two in Normandy after conquering it in the 10th century.