Lady Mary was last seen by Edward in February, and was kept informed about the state of her half-brother's health by Northumberland and through her contacts with the imperial ambassadors.
Aware of Edward's imminent death, she left Hunsdon House, near London, and sped to her estates around Kenninghall in Norfolk, where she could count on the support of her tenants.
Northumberland sent ships to the Norfolk coast to prevent her escape or the arrival of reinforcements from the continent.
He delayed the announcement of the king's death while he gathered his forces, and Jane Grey was taken to the Tower on 10 July.
On the same day, she was proclaimed queen in the streets of London, to murmurings of discontent.
The Privy Council received a message from Mary asserting her "right and title" to the throne and commanding that the Council proclaim her queen, as she had already proclaimed herself.
The Council replied that Jane was queen by Edward's authority and that Mary, by contrast, was illegitimate and supported only by "a few lewd, base people".

Northumberland soon realised that he had miscalculated drastically, not least in failing to secure Mary's person before Edward's death.
Although many of those who rallied to Mary were conservatives hoping for the defeat of Protestantism, her supporters also included many for whom her lawful claim to the throne overrode religious considerations.
Northumberland was obliged to relinquish control of a nervous Council in London and launch an unplanned pursuit of Mary into East Anglia, from where news was arriving of her growing support, which included a number of nobles and gentlemen and "innumerable companies of the common people".
On 14 July Northumberland marched out of London with three thousand men, reaching Cambridge the next day; meanwhile, Mary rallied her forces at Framlingham Castle in Suffolk, gathering an army of nearly twenty thousand by 19 July.

It now dawned on the Privy Council that it had made a terrible mistake.
Led by the Earl of Arundel and the Earl of Pembroke, on 19 July the Council publicly proclaimed Mary as queen; Jane's nine-day reign came to an end.
The proclamation triggered wild rejoicing throughout London.
Stranded in Cambridge, Northumberland proclaimed Mary himself—as he had been commanded to do by a letter from the Council.
William Paget and the Earl of Arundel rode to Framlingham to beg Mary's pardon, and Arundel arrested Northumberland on 24 July.
Northumberland was beheaded on 22 August, shortly after renouncing Protestantism.
His recantation dismayed his daughter-in-law, Jane, who followed him to the scaffold on 12 February 1554, after her father's involvement in Wyatt's rebellion.
Lady Mary was last seen by Edward in February, and was kept informed about the state of her half-brother's health by Northumberland and through her contacts with the imperial ambassadors. Aware of Edward's imminent death, she left Hunsdon House, near London, and sped to her estates around Kenninghall in Norfolk, where she could count on the support of her tenants. Northumberland sent ships to the Norfolk coast to prevent her escape or the arrival of reinforcements from the continent. He delayed the announcement of the king's death while he gathered his forces, and Jane Grey was taken to the Tower on 10 July. On the same day, she was proclaimed queen in the streets of London, to murmurings of discontent. The Privy Council received a message from Mary asserting her "right and title" to the throne and commanding that the Council proclaim her queen, as she had already proclaimed herself. The Council replied that Jane was queen by Edward's authority and that Mary, by contrast, was illegitimate and supported only by "a few lewd, base people".
Northumberland soon realised that he had miscalculated drastically, not least in failing to secure Mary's person before Edward's death. Although many of those who rallied to Mary were conservatives hoping for the defeat of Protestantism, her supporters also included many for whom her lawful claim to the throne overrode religious considerations. Northumberland was obliged to relinquish control of a nervous Council in London and launch an unplanned pursuit of Mary into East Anglia, from where news was arriving of her growing support, which included a number of nobles and gentlemen and "innumerable companies of the common people". On 14 July Northumberland marched out of London with three thousand men, reaching Cambridge the next day; meanwhile, Mary rallied her forces at Framlingham Castle in Suffolk, gathering an army of nearly twenty thousand by 19 July.
It now dawned on the Privy Council that it had made a terrible mistake. Led by the Earl of Arundel and the Earl of Pembroke, on 19 July the Council publicly proclaimed Mary as queen; Jane's nine-day reign came to an end. The proclamation triggered wild rejoicing throughout London. Stranded in Cambridge, Northumberland proclaimed Mary himself—as he had been commanded to do by a letter from the Council. William Paget and the Earl of Arundel rode to Framlingham to beg Mary's pardon, and Arundel arrested Northumberland on 24 July. Northumberland was beheaded on 22 August, shortly after renouncing Protestantism. His recantation dismayed his daughter-in-law, Jane, who followed him to the scaffold on 12 February 1554, after her father's involvement in Wyatt's rebellion.
Edward VI of England