Thomas of Palmela character is fictional and was probably based on an illegitimate son of John III, king of Portugal from 1502 to 1557. Nor could he be heir to the Portuguese king - his heir was his grandson, Sebastian.
In the series, Thomas is described as a bastard of John III and his only son. In fact, John III had six sons and three daughters.
They all died before their father, but the fifth, João Manuel, left a son, Sebastian.
Even if Thomas had existed, helping Mary against the English would be absurd, because Portugal and England were allies since 1390, and have remained so until the present day.
In the series, Thomas is described as a bastard of John III and his only son. In fact, John III had six sons and three daughters.
They all died before their father, but the fifth, João Manuel, left a son, Sebastian.
Even if Thomas had existed, helping Mary against the English would be absurd, because Portugal and England were allies since 1390, and have remained so until the present day.
