"Her condition deteriorated this morning and her doctors were called.
Queen Elizabeth died peacefully in her sleep at 3.15 this afternoon at Royal Lodge.
"The Queen was at her mother's bedside."
The Queen Mother's funeral took place on April 9 at Westminster Abbey and was broadcast to the world.
It was shown live both on BBC and ITV, attracting 10 million viewers.
There was some controversy over the poem chosen by Queen Elizabeth II to be read at the service.
The monarch opted for a work of unknown provenance, called ‘She is Gone', which caused quite a stir.
It is thought that the poem was written for a magazine or condolence card rather than by a renowned poet.
According to the Times, the poem was sent to Buckingham Palace on a memorial card sent by a member of the public.
It had previously been used to commemorate the deaths of a 52-year-old Scottish alcoholic, a 15-year-old high school baseball player and an Australian glam rock star.
The poem grew in popularity as it was shared though the internet.
However, the deputy of the Times Literary Supplement at the time, Alan Jenkins, was highly dismissive of the unknown poet's creative talents.
Mr Jenkins, a poet himself, described the poem as "a nothing piece of writing".
Buckingham Palace defended the Queen's choice, saying the poem reflected her thoughts on how the country should celebrate her mother's life.
Andrew Motion, the UK's Poet Laureate in 2002, also came to the defence of the monarch, saying the poem's value depended on the comfort it gave the bereaved
The poem formed a preface to the order of service, and began: "You can shed tears that she is gone or you can smile because she has lived.
"You can close your eyes and pray that she'll come back or you can open your eyes and see all she's left."
It was on March 30 2002 that the 101-year-old Queen Mother passed away in her sleep, some 50 years after the death of her husband, King George VI. She died at her Windsor residence, Royal Lodge, with the time of death fixed at 3.15pm. Her Majesty kept her mother company throughout her last moments, sitting by her bedside.
The announcement of the Queen Mother's death was made public by Buckingham Palace on behalf of the monarch a little while later.
The official statement said: "The Queen, with the greatest sadness, has asked for the following announcement to be made immediately: her beloved mother, Queen Elizabeth, died peacefully in her sleep this afternoon at Royal Lodge, Windsor.
"Members of the royal family have been informed."
The palace spokesman continued: "Queen Elizabeth the Queen Mother had become increasingly frail in recent weeks following her bad cough and chest infection over Christmas.