British citizens have an abundance of rights, from marriage and civil partnerships to the right to protest and the right to make a complaint against the government--and plenty more. With these rights come an abundance of responsibilities. British citizens are expected to contribute to society in certain ways to help the country thrive domestically and operate smoothly. While they aren't required to do all of these things, the government sees them as duties for citizens.
The government expects loyalty from its citizens in ways that can't necessarily be enforced by law, but which are still duties. British citizens are expected to take pride in being from and/or living in Britain, honour the queen, and participate in and recognise national holidays and activities. This loyalty has been expected from British citizens--in many different capacities--for hundreds of years. Citizens are, however, required to abide by laws established by the British government and not plot against the government. All of these things are part of being a loyal British citizen.
The government does not require British citizens to vote, but it expects citizens to vote as a civic duty, believing that results are not accurate and democracy is defeated in some capacity when citizens do not vote. All British citizens who are at least 18 years old can vote unless they are in prison.
British citizens are required to report for jury service when called and attend for as long as it takes to find a verdict. Being a juror gives citizens a chance to play an important and vital role in the justice system in the U.K., and prior knowledge of the justice system is not required. Jurors are simply required to hear the evidence, discuss the case and decide if the defendant is guilty or not guilty. In Britian, minor criminal cases are judged without a jury in the Magistrate's Court; in middle-ranking cases, the defendant can choose jury or no jury in the Crown Court; and in serious criminal cases, the jury has to decide the sentence in the Crown Court.