The Queen has signed the Commonwealth's historic charter despite still recovering from the symptoms of gastroenteritis.
Making her first official public appearance for more than a week she described the document as capturing "the core values and aspirations" of the family of nations, before putting her name to it.
The Queen was forced to miss the annual Commonwealth Day service earlier as she was still recovering.
But she looked well and in good spirits when she arrived at Marlborough House in central London, home of the Commonwealth, with the Duke of Edinburgh for the signing.
Before the ceremony began she told guests who included High Commissioners from across the globe: "The Charter I will sign today, on behalf of you all, represents a significant milestone as the Commonwealth continues its journey of development and renewal.
"We have now, for the first time, a single document that captures the core values and aspirations of the Commonwealth and all its members."
For the first time one document has been agreed by the 54 member states which enshrines a comprehensive range of principles and values, from gender equality to rule of law.
But it has proved controversial amongst gay rights groups with the words "other grounds" under the human rights topic being seized upon by activists, with one group claiming the Queen is supporting lesbian and gay issues, while another suggests she has made no commitment to gay equality.
The charter states: "We are implacably opposed to all forms of discrimination, whether rooted in gender, race, colour, creed, political belief or other grounds."