LONDON — The 800th anniversary on Monday of Magna Carta, a medieval political truce that inspired protections for some of the world’s most cherished liberties, prompted a range of celebrations in Britain that included a ceremony involving Queen Elizabeth II and a national beer day.

In Runnymede, England, the site 20 miles from London by the banks of the Thames where the document was signed, the queen and Prime Minister David Cameron attended an official commemoration, where Mr. Cameron noted the historical legacy of Magna Carta.

“Liberty, justice, democracy, the rule of law — we hold these things dear,” he said, “and we should hold them even dearer for the fact that they took shape right here, on the banks of the Thames.”

There have also been dozens of local events throughout the country, including seminars and talks, a Magna Carta musical, and plans for a national day to say “Cheers to Magna Carta” with beer, which has traditionally been Britain’s favorite alcoholic beverage. That was prompted by a call in the document for a standard measure for wine, ale and corn.