The "commoner" who is to marry Sweden's crown princess next week has artistocratic roots, according to a new book.

Daniel Westling has been mocked for his provincial roots and country accent, and has undergone careful grooming by courtiers, language tutors and a public relations agency ahead of his wedding later this month to Crown Princess Victoria.

Sweden's King Carl XVI Gustav was reportedly initially hostile to the idea of his 32-year-old daughter marrying the commoner.

But, according to the genealogist Björn Engström, the former fitness instructor is descended from both Swedish and Finnish aristocracy.

Mr Westling can count among his distant relatives members of parliament, courtiers, royal retainers and even a woman convicted of witchcraft.

One of Mr Westling's ancestors was a member of the court of the 16th century Swedish King Karl IX and he can also trace lineage back to the aristocratic Svinhufvud family.

That connection means that he is also distantly related to Pehr Evind Svinhufvud, who was president of neighbouring Finland in the 1930s....