The Queen is to make history tomorrow when she becomes the first British monarch to reach their sapphire jubilee.

On February 6, the anniversary of the day she became Queen, Elizabeth II will have reigned for 65 years.

But no grand festivities are planned to mark the head of state's new milestone.

The Queen is not due to be out and about on official engagements on the landmark day.

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The sovereign, who missed church over Christmas because of a heavy cold, will undoubtedly be matter of fact about this historic occasion.

In 2015, when she thanked the nation for its kind messages after overtaking Queen Victoria to become the longest-reigning monarch in British history, she admitted bluntly that the royal record was "not one to which I have ever aspired".

She added: "Inevitably, a long life can pass by many milestones. My own is no exception."

The Queen celebrated her 90th birthday last year and had a busy schedule commemorating the occasion, with a walkabout, beacon lighting and a black-tie dinner for family and friends in Windsor on her actual birthday.

A weekend of national celebrations was held for her official birthday in June.

It is likely that any large-scale jubilee celebrations will be reserved for the Platinum Jubilee in 2022 - although any events will take into account the fact that Queen is due to turn 96 that year.

Prince William is about to become a fulltime royal this year and will increase his official duties on behalf of the Queen.

William and the Duchess of Cambridge are carrying out an engagement tomorrow but not to do with the Queen's record-breaking reign.

The anniversary of her accession to the throne in 1952 is a poignant time for the Queen, marking the day her father George VI died. She often spends Accession Day privately at Sandringham. Traditional royal gun salutes will be staged in London tomorrow.

- AAP