Steganography in Princess Elizabeth's Letter

The images shown below are images of the letter Princess Elizabeth sent to Dowager Queen Katherine Parr, (c.June 1548 (SP10/2 f.84c)). Elizabeth had left Parr's household because Katherine had found Elizabeth in an embrace with Thomas Seymour, Katherine's husband.

The clue to this overlay is the line “you sayd you wolde warne me of al evelles.” The message revealed is:

“[A]t my departure,...truly, I was replete with child. I [am] to be born with a child, for [I am] vndoubtful of helthe. [Regarding Thomas Seymour], sayd you would warne me of al evelles (his plots?). Seymour had not a good opinion of me.”

It is noteworthy that the word "manifolde" appears near the message on the overlay. The words "fold," "infold," and "unfold" were terms used in Elizabethan times to refer to encipherment and decipherment.

This message seems to indicate that Elizabeth using this particular method of hiding messages in text before the method was used in the First Folio. Was this a method of hiding message employed by the Freemasons, Rosicrucians, and the Tudors?