But there are no grand festivities planned to mark the head-of-state’s new milestone. The Queen is not due to carry out any official engagements on the landmark day.
As is usual on Accession Day, the monarch will be spending it privately at her Sandringham Estate in Norfolk.
The sovereign, who missed church over Christmas due to 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 on 21 April.
A weekend of national celebrations, including a party on The Mall, 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.
The Duke of Cambridge is about to become a full-time royal this summer and will increase his official duties on behalf of the Queen.
William and the Duchess of Cambridge are carrying out an engagement today, but not to do with the Queen’s record-breaking reign.
They will be attending Place2Be’s Big Assembly at a primary school in north London to mark Children’s Mental Health Week.
The anniversary of Elizabeth’s 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, staying there through the Christmas period. She usually makes her return to Buckingham Palace a few days later.
Royal gun salutes will be staged in London today, as is the tradition. A 41-gun salute will be fired by the King’s Troop Royal Horse Artillery in Green Park at noon.
The Band of the Royal Artillery will play a selection of celebratory music close to the firing position, and 89 horses will pull six First World War-era 13-pounder field guns into position in the park.
A 62-gun salute by the Honourable Artillery Company will be fired at the Tower of London at 1pm.
Yesterday well-wishers were greeted with a smile as the Queen went on a walkabout. She gathered up bouquets from the waiting crowds after the church service at St Peter and St Paul in West Newton, Norfolk.
Three-year-old Jessica Atfield, who dressed specially for the occasion in a Union flag skirt, was delighted when she got to hand over a bunch of flowers to the Queen.
A David Bailey portrait of the Queen has been re-issued to commemorate the 65th anniversary of the accession to the throne.
The photograph shows the head of state wearing a suite of sapphire jewellery given to her by King George VI as a wedding gift in 1947.
Sapphire is the 65th anniversary gemstone and the King’s gift to his eldest daughter, then Princess Elizabeth, featured a glittering necklace, dating from 1850 and made of 16 large oblong sapphires surrounded by diamonds, with a pair of matching sapphire and diamond drop earrings.
The Queen has added a sapphire and diamond tiara – made from a necklace that originally belonged to Princess Louise of Belgium – and a bracelet in 1963 to the collection to complement the original sentimental pieces.
She had the necklace shortened and the largest stone made into a pendant.
The photograph was taken and first issued in 2014 after being commissioned for the government’s “Great” campaign, which aims to promote the UK abroad.
The Royal Mail has issued a Sapphire Blue £5 stamp to commemorate the anniversary. Last year, the Royal Mail issued a series of ten postage stamps to mark the monarch’s 90th birthday, with Prince George featuring on a stamp for the first time.
The image of the Duke and Duchess of Cambridge’s two-year-old son was captured by photographer Ranald Mackechnie as part of a wider portrait featuring four generations of the House of Windsor, comprising the Queen and three future monarchs: Charles, Prince of Wales, William, Duke of Cambridge and Prince George of Cambridge.