His call to the British people is to take back their country from this rule, while he helps by taking down the central leader and his sects (named after parts of the body, such as Finger, Nose, and Voice). V is a vigilante, for certain, but he is also the only hope that the people held under a conservative, fascist regime have.
This is the movie version of Alan Moore's comic V for Vendetta.
The film was fair and kept the gay and lesbian component of it as central as it was in the comic (which is important to the motivation of the characters but tangential to the plot).
Smarmier than the graphic novel, but well worth a watch.