The King's Writers were the royal scribes of Gondor. This entailed making the official records of Gondor, working directly with original sources.
Findegil, a King's Writer of renown presumably under the Kingship of Eldarion in the Fourth Age, is known to have made at least one copy of the Red Book of Westmarch in Minas Tirith. Indeed, in Fo.A. 172, he finished a copy to create the Thain's Book. This copy was the only one to include Bilbo's complete Translations from the Elvish, which Bilbo had composed while at Rivendell during his 'retirement' there.