Vikings centres on their arrival and the disruption it brought, but that only continued for a very short time," says Dr Maire Ni Mhaonaigh, a professor of Celtic studies who organised the recent Cambridge conference. "Afterwards, they started building settlements and interacting with the locals." Raiders adopted the host language and, over one or two generations, took local wives, adopted local names, adapted to local social structures, often converted to Christianity and became part of main-stream society. Modern Britons, says Dr Mhaonaigh, can take a lesson from such a positive example of immigration.

If they were so nice, why invade?

The Vikings' big problem was their native Scandinavia: arable land was scarce, the seasons hostile, so they were always looking for greener pastures. And they had the technology to do so. Their longships were fast and sea-worthy, their crews astoundingly adept at navigating them. By salting and storing cod, they could make extraordinary journeys. These included the five recorded Viking expeditions to North America between 985 and 1011 and settling as far afield as Constantinople, Greenland and Newfoundland. This global diaspora is the truly remarkable thing about the Vikings: they travelled as far as the Volga River in Russia and fought as mercenaries for the Byzantine Empire, reaching North Africa, Jerusalem and Baghdad.

What about their influence over here?

Danish raids during the reign of King Alfred the Great (871-899), split England in two: Wessex and English Mercia on the one side, and the Danelaw (the East of England) on the other. Alfred and his descendants eventually reclaimed the Danelaw, but it kept its own identity. Things got even more complicated in the early 11th century, when the Danish King Sweyn Forkbeard and his son Canute invaded, defeating the English king, Ethelred the Unready, himself backed by Danish forces. Once Canute became King, even more Danes settled, so by 1066 almost all English leaders, including King Harold, were at least half Danish. Even the Normans, when they arrived, were partly Viking (Danish Vikings conquered Normandy as early as the 8th century), so at the Battle of Hastings there was Viking blood on every side. In a sense, Vikings have ruled us ever since.

So have we now changed our minds about the Vikings?

Not entirely. The authoritative Cultural Atlas of the Viking World still maintains that the Vikings attacked Britain with "startling and unparalleled ferocity". Alfred Smyth, professor of medieval history at Kent University, insists there must have been something uniquely terrifying about them. "When they got psyched up," he says, "they could butcher an entire population - something new to warfare in the early Middle Ages." In a recent letter to the Daily Telegraph, historian David Hipshon insists that attempts to reinvent the Vikings smack of trendy moral relativism. "The Nazis may have to wait a few years," he writes, but sooner or later "someone will organise a conference to highlight their technological prowess and cleanliness."