Mary was alone in the world at the age of just seven months and with no inheritance to help support her she was, it would seem, a burden. Evidence for this can be found in a letter from the Duchess to William Cecil where she asks for financial help. In the January of 1550, Mary was awarded what was left of her inheritance, however, no claim was made on it and therefore it has been supposed that the poor child died before that date.
In a biography of Catherine Parr, written in the 19th century, it states that Mary lived into adulthood and married. However, a recent biography suggests that Mary died, just as the above dates suggest, in 1550. In a poem dated to 1573 is said to refer to Mary.
Of her own life
My queenly mother
Bore with the pangs of labour
Sleep under this marble
An unfit traveller.
If Death had given me to live longer
That virtue, that modesty, That obedience of my excellent Mother
That Heavenly courageous nature
Would have lived again in me.
You are, fare thee well
Because I cannot speak any more, this stone
Is a memorial to my brief life