Originally Posted by Tatiana Maria
Are you sure that he was created a Prince of Sweden? I only read that he was created HRH by his wife and Parliament, and the title Prince of Sweden was not officially in use by the royal family at the time (princes in the line of succession were strictly Sveriges Arvfurste up to 1982, when the present King altered it to Prins av Sverige).
From where I've read (only secondary sources) he was created Prince of Sweden. I did find two mentions of him on page 26 of the SOU* 1977:5:
1 - "Added to that (Princess) Ulrika Eleonora's husband, the Hereditary Prince Frederik of Hesse was a member of the Reformed Church"
2 - "the following year the Queen abdicated in favour of her husband Prince Frederik" implying (atleast that's how I interpret it) that there had been a change of title when his wife was elected queen (though the SOU doesn't style him as Prince of Sweden).
Regarding arvfurste he could never have carried the title without being included in the line of succession which he never was.
*For those of you who don't know an SOU is the name of an official series of reports of committees appointed and convened by the*Government of Sweden for the analysis of issues in anticipation of a proposed legislation before the*Riksdag or the issuance of*ordinances.