Historian Dr. Sam Willis looks at the history of both the successful and unsuccessful attempts to invade Britain. Dr. Willis begins with invasions dating back 10,000 years ago, looking at the Beaker People and the use of Stone Age weapons. Moving forward he goes for a ride in an Iron Age chariot, examines the problems the Romans had landing in the country, and gets to grips with the technology behind Viking longboats. Invasion! With Sam Willis is on BBC Four at 21.00.