Boudica (hey - there are several spellings and even more pronunciations) was Queen of the Iceni tribe, a celtic tribe which occupied the land quite happily as an independant ally of Rome, in the area that is now Norfolk. On the death of Boudica's husband, the king Prasutagus, the Romans failed to honour an arrangement to leave Boudica and her daughters half the kingdom and instead flogged Boudica and raped her daughters. Understandably this made her a little cross, and her people, allied with the Trinovantes (our Essex celtic tribe) stomped the Romans good and proper. Sadly in the end she was defeated (although not without making a real mess of Roman Britain) and killed herself.
The BBC Horrible Histories website is phenomenal for sharing all this stuff with kids and getting a handle on it. I just love this song, which is not only hilarious, it seems to tell it much better than any Wikipedia page could do!
I am proud to have rampaging Iceni Warrior Queens as part of my Essex heritage. Should the Romans ever get too up-themselves again Queen B only has to give me a shout and I'll be sharpening my axe and joining the throngs to march on Londinium. (Is somebody bringing the mead?)