The Queen has been force to cancel her appearance at a major service celebrating the Commonwealth as she is continuing to recover from her recent bout of gastroenteritis, Buckingham Palace said today.
The Queen had been due to attend the Commonwealth Day Observance at London's Westminster Abbey that will see High Commissioners from across the globe in the congregation and a key-note address from Sir Richard Branson.
The Duke of Edinburgh will now be the only senior royal representative but the Palace said the Queen would attend an evening reception where she will sign the new Commonwealth charter.
The monarch spent 24-hours in hospital last week being treated for the illness which leaves sufferers with vomiting and diarrhoea.
Buckingham Palace had said on Friday that the Queen would attend today's service and it was "business as usual".
She was struck down by the stomach bug just over a week ago and spent last Sunday night at the private King Edward VII's Hospital in central London before being discharged on Monday.
Concerns were raised about the 86-year-old Queen's general well-being as it was the first time she had been admitted to hospital in almost 10 years.
But she left the hospital looking well and cheerful.
Her engagements for last week were cancelled, including a brief visit to Rome to meet Italy's president.
A Buckingham Palace spokeswoman said: "This time last week she was in hospital but she's in great spirits and apart from this is in good health and will be going to the reception in the evening.
"It's just the tail end of the symptoms, her condition has not worsened at all."
The Palace announced the cancellation in a short statement: "The Queen will regrettably no longer attend the Commonwealth Observance at Westminster Abbey today as she continues to recover following her recent illness."
It added: "The Queen hopes to undertake some of her official engagements planned for the rest of this week."
Despite missing the Westminster Abbey service, the Queen will still sign the Commonwealth's new charter at Marlborough House in her role as head of the family of nations.
For the first time it enshrines a number of principles and values, from gender equality to rule of law, in one document which has been agreed by the 54 member states.
The words "other grounds" under the human rights topic have been seized upon by gay rights campaigners, 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."
Ben Summerskill, chief executive of the gay and lesbian rights group Stonewall, said: "This is the first time that the Queen has publicly acknowledged the importance of the 6% of her subjects who are gay.
"Some of the worst persecution of gay people in the world takes place in the Commonwealth countries as a result of the British Empire."
A Stonewall spokesman said more than 50 Commonwealth nations have laws that prohibit same-sex relationships.
But gay rights campaigner Peter Tatchell said the Queen had made no "explicit commitment" to gay equality.
He added: "Not surprisingly, the Commonwealth Charter does not include any specific rejection of discrimination based on sexual orientation or gender identity. This was vetoed by the homophobic majority of member states. They blocked its inclusion.
"This makes the Queen's charter-signing even less of a big deal. It is certainly not the breakthrough for the lesbian, gay, bisexual and transgender rights that some people are claiming."
In her pre-recorded Commonwealth message to be broadcast at the service, the Queen will say that the values of the new charter have "special emphasis" on including everyone in striving for a better future.
She will say: "Ambition and curiosity open new avenues of opportunity.
"That is what lies at the heart of our Commonwealth approach: individuals and communities finding ways to strive together to create a better future that is beneficial for all."
She will add: "Our shared values of peace, democracy, development, justice and human rights - which are found in our new Commonwealth charter - mean that we place special emphasis on including everyone in this goal, especially those who are vulnerable."
The charter, agreed by all Commonwealth heads of government last December, will also endorse new legislation ending discrimination against women in the line of succession to the British throne.
The Government is introducing new legislation along these lines which will mean the Duke and Duchess of Cambridge's first baby can succeed to the throne, regardless of whether the child is a girl or a boy.
A spokeswoman for the Commonwealth Secretariat said the charter "speaks to the values and principles of the Commonwealth generally".
"It does not mention gay rights specifically, but rather human rights more broadly.
"The notion that the Queen has pledged to promote gay rights is an interpretation that certain publications who have reported this have formed on their own.
"The Queen, as in all matters, is apolitical on matters of policy."