The Queen returned to public engagements on Monday evening, focused, smiling and clearly recovered from her recent bout of gastroenteritis.
Her Majesty, professional in a duck-egg blue dress and tweed jacket, attended a Commonwealth Day reception at Marlborough House for the historic signing of the Commonwealth Charter.
The Commonwealth is an organisation comprised of countries that previously formed part of the British Empire. The Queen is still head of state for some of them, including Canada, Australia and New Zealand.
Its new document binds the 54 diverse member states with shared principles of gender equality, democracy and freedom of expression. The Charter marks the first time that Commonwealth countries have agreed on a single document outlining these values.
Commonwealth Day had got off to a disappointing start when the Queen was forced to pull out of Westminster Abbey's annual ceremony on the advice of her doctors.
A statement issued by the sovereign's press secretary said: "The Queen will regrettably no longer attend the Commonwealth Observance at Westminster Abbey today as she continues to recover following her recent illness.
"The Duke of Edinburgh will attend the Observance as planned.
"However, Her Majesty will still attend the Commonwealth Reception at Marlborough House this evening to sign a new Commonwealth Charter.
"The Queen hopes to undertake some of her official engagements planned for the rest of this week."