[Arvegil145]

Here might be a good place to suggest an addition from The Nature of Middle-earth, 'Beards', p. 188:

The matter of Denethor and his sons is not so clear. But I explained this by referring to Gandalf’s remarks concerning Denethor: that “by some chance” the Númenórean was nearly “true” in him – meaning that by some event in Denethor’s ancestry which Gandalf had not investigated, he had this mark of ultimately “royal” descent. This “chance”, I said, was to be seen in the fact that Húrin the First Steward (from whom Denethor was directly descended) must have been a kinsman of King Minardil (see L.R. III 319, 332, 333) sc. of ultimately royal descent, though not near enough in kinship for him or his descendants to claim the throne. I did not but could have noted the following points. The Kings of Gondor had no doubt had “stewards” from an early time, but these were only minor officials, charged with supervision of the King’s halls, houses, and lands. But the appointment of Húrin of Emyn Arnen, a man of high Númenórean race, was different. He was evidently the chief officer under the crown, prime counsellor of the King, and at appointment endowed with the right to assume vice-regal status, and assist in determining the choice of heir to the throne, if this became vacant in his time. These functions all of his descendants inherited. It may also be noted that they had Quenya names, which had long been a privilege only of those of proved royal descent.