Although he faced several years of worsening health, including lung cancer, George VI died unexpectedly in his sleep at Sandringham in 1952.

The Queen normally spends the joint anniversary of her accession to the throne and her father's death in private, staying out of the public eye.

Close to her father as a child, Elizabeth was said to be similar to him in character and, according to royal author Sarah Bradford, they shared a ``dedicated professionalism''.

When the king died, Princess Elizabeth was thousands of miles away in Kenya, watching big game in the Treetops Hotel with the Duke of Edinburgh, unaware of the momentous duty that had fallen upon her shoulders.

They were resting after returning to the Sagana Lodge, which had been given to them as a wedding present by the people of Kenya, when the message was given to Philip. He broke the news to his wife while they were alone.

Princess Elizabeth, now Queen, was ready to fulfil her duty.

Lord Charteris, her then-private secretary, remembered seeing her seated at her desk in the Lodge appearing ``very composed''.

Asked what name she wished to use as Queen, she is said to have replied simply: ``My own name, of course.''