To explain what the Domesday Book was, we'll need to go back in time a bit. About 1000 years, actually, to early English history...

In the year 1066 William The Bastard of Normandy invaded England in what became known as the Battle of Hastings. Defeating the English, he took the crown and was named William I of England. You probably know him better as William the Conquerer, however. Same guy, just a bunch of different titles.

Twenty years after the invasion, it appears that King William was sitting with some of his royal advisors, complaining about taxes (yeah, even a thousand years ago The Man was looking for tax revenue!) when this transpired:

"After this had the king a large meeting, and very deep consultation with his council, about this land; how it was occupied, and by what sort of men. Then sent he his men over all England into each shire; commissioning them to find out 'How many hundreds of hides were in the shire, what land the king himself had, and what stock upon the land; or, what dues he ought to have by the year from the shire."

And, oh yes, there really is a book:

So basically the book is the very first census report, and it proves a hugely important historical document because it lets us see how land was allocated and who owned what all those centuries ago.

The BBC has a nice mini-site about the Domesday Book, where it explains, in a rather Brit-centric manner:

"It is our earliest public record, the foundation document of the national archives and a legal document that is still valid as evidence of title to land.

Based on the Domesday survey of 1085-6, which was drawn up on the orders of King William I, it describes in remarkable detail, the landholdings and resources of late 11th-century England, demonstrating the power of the government machine in the first century of the new Millennium, and its deep thirst for information.

It was an exercise unparalleled in contemporary Europe, and was not matched in its comprehensive coverage of the country until the population censuses of the 19th century - although Domesday itself is not a full population census, and the names that appear in it are mainly only those of people who owned land."

Wondering what these early census takers were asking the land owners? Here's the list of questions:

• What the manor was called
• Who held it at the time of King Edward (the king who was deposed in the Battle of Hastings when William invaded)
• Who holds it now
• How many hides there are (measurement of land for taxation purposes, between 60 and 120 acres)
• How many ploughs held by the lord and how many belonging to the peasants
• How many villeins (the wealthiest of the unfree peasants who had to pay his lord labour service and rent)
• How many cottars (an unfree peasant with a holding of land up to 5 acres)
• How many slaves (unfree man or woman)
• How many freemen
• How many sokemen (equivalent to a freeman but owing dues to his lord for his holding)
• How much woodland, meadow and pasture.
• How many mills and fisheries
• How much had been added to or taken away from the estate
• What it used to be worth altogether
• What it is worth now

What I find so amazing about this is how contemporary so much of this seems. Remember, it was compiled ten centuries ago. That's a lotta time!

So in the terrific series Foyle's War, the character is basically saying "this land has been in our family for hundreds of years, all the way back to the survey of 1086". Make sense now?