Story highlights A large part of the British Antarctic Territory is named for Queen Elizabeth II

She attends her first Cabinet meeting at 10 Downing Street

As head of state, the queen has to remain strictly neutral

The visit is part of her diamond jubilee celebrations

British ministers had a special guest in their midst during their Cabinet meeting Tuesday: Queen Elizabeth II.

It was a historic occasion because it is thought to mark the first time a monarch has attended such a session since Queen Victoria more than a century ago.

The monarch, wearing blue, was greeted at the door of 10 Downing Street by Prime Minister David Cameron.

The queen has not attended a Cabinet meeting before now because her involvement in Britain's political life is generally formal or ceremonial.

Her role is clear: "As Head of State The Queen has to remain strictly neutral with respect to political matters, unable to vote or stand for election," according to the British Monarchy's website

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Her presence as an observer Tuesday coincides with the end of the yearlong celebration marking her 60 years on the throne. During that time, the United Kingdom has had 12 prime ministers.

The session lasted 90 minutes, during which ministers presented her with a gift they personally paid for to mark her diamond jubilee.

The queen also visited the Foreign and Commonwealth Office on Tuesday, where she was paid a rather unusual tribute: the naming after her of 169,000 square miles of the Antarctic.

Foreign Secretary William Hague said the southern part of the British Antarctic Territory had been designated "Queen Elizabeth Land" in honor of her 60-year reign.

The previously unnamed territory is nearly twice the size of the United Kingdom and about a third of the whole land mass of the British Antarctic Territory, Hague said.

The queen's visit to the Foreign Office, only her second in the past six decades, is the final official engagement of her busy jubilee year.