Bizarre thinking. If Elizabeth pre-deceased Mary Stuart, what exactly would Elizabeth lose ? She'd be already dead.
You have some quaint notion that a Protestant nation which had been through several religious upheavals would assent to the accession of a Catholic woman who was not even steadfast to her own faith- Mary after all married a divorced Protestant in the Protestant rite, willingly accepted the Scottish Protestant ascendancy for the sake of a throne, and was willing to share power with her Protestant son and ignore 'Regnans In Excelsis' if she could be set free.
They were joint rulers. Edmund ruled Wessex, Cnut the rest.
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