The Queen Of England and Prince Philip pose for affectionate 70th wedding anniversary portrait celebrating the most successful marriage in British royal history (Details, pics)

It is a portrait of historic stability and enduring affection.

On the eve of their 70th wedding anniversary, the Queen and the Duke of Edinburgh are celebrating the most successful marriage in British Royal history by releasing a series of glorious official images.

The portraits – dignified yet clearly affectionate – mark an astonishing milestone in Her Majesty’s record-breaking lifetime of service with the unwavering support of Prince Philip by her side.

They were taken in the White Drawing Room at Windsor Castle earlier this month by British photographer Matt Holyoak, and show the Monarch with a smile playing on her lips.

The Queen, 91, wears a cream day dress by Angela Kelly which she also wore at the service marking her diamond wedding anniversary at Westminster Abbey a decade ago.

In a touching tribute to Prince Philip, 96, she has pinned to her left shoulder the brooch in yellow gold, carved ruby and diamond, designed by Andrew Grima, which the Duke gave her as a personal gift in 1966.Behind her, the Duke wears a dashing light tweed jacket and sharply creased grey flannel trousers. He appears relaxed and healthy after his retirement from official duties in the autumn.

The Queen is said to be keen to mark her platinum wedding anniversary privately, welcoming her closest family and friends to a private dinner party in the State Apartments at Windsor Castle tomorrow evening.

It will be in sharp contrast to their wedding at Westminster Abbey on November 20, 1947 – which was celebrated around the world.

... FRAMED BY FIRST ROYAL GEORGE AND CHARLOTTE

For as the Queen and Prince Philip celebrate the longest marriage in British Royal history by a comfortable margin, looking down on them from either side are the couple who previously held that honour.

Just out of shot in the official image above are two portraits that hold a special significance.

Their elegant oil portraits, by English painter Thomas Gainsborough, were commissioned by the King in 1781 and marked 20 years since his coronation.

King George III, the Queen’s great-great-great-great grandfather, was married to Queen Charlotte for 57 years until her death in 1818.

The couple only met on their wedding day and George ascended to the Throne just two weeks later.