In a letter written to mark the 70th anniversary of her accession to the throne, Elizabeth said the occasion had given her pause to reflect upon the loyalty and affection shown to her by the British public.

She said she hoped Charles and Camilla would receive the same support.

"(It) is my sincere wish that, when that time comes, Camilla will be known as Queen Consort as she continues her own loyal service," Elizabeth said.

Charles and Camilla, long-time lovers, were married in 2005 in a civil ceremony in Windsor. Their Clarence House residence said on Saturday that they were "touched and honoured by Her Majesty's words".

Elizabeth's move reflects a wider acceptance of Camilla's status as a royal.

Tabloid newspapers no longer target her as they did in the decade following the death in 1997 of Charles' first wife, Princess Diana.

Camilla - whose current title is Duchess of Cornwall - now regularly represents the royal family alongside Charles during official duties.

Throughout British history, the wife of a king typically is given the title Queen Consort. At the time of their marriage, it had been officially decided that Camilla would use the title Princess Consort if Charles were to become king.

While Elizabeth on Sunday celebrates 70 years on the British throne - an unprecedented stretch - the anniversary comes at a time of tumult for the royal family.

From the U.S. sex abuse court case facing her son Prince Andrew to allegations by her grandson Prince Harry and his wife of racism in the royal household, rarely has the 95-year-old Elizabeth's family faced such scrutiny and damaging headlines.

Last year she lost her husband of 73 years, Philip, whom she acknowledged in her letter on Saturday.

"I was blessed that in Prince Philip I had a partner willing to carry out the role of consort and unselfishly make the sacrifices that go with it. It is a role I saw my own mother perform during my father's reign," Elizabeth said.

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