In the past he has been confounded with Robert of Chester (Latin Robertus Castrensis), another English translator active in Spain in the mid-twelfth century; and at least one modern scholar believes they are the same person.
[1] Robert's byname, Ketenensis or on one occasion de Ketene, is usually taken to refer to Ketton, a village in Rutland, a few miles from Stamford, Lincolnshire.
In the accompanying letter he named the translator as "Robert of Ketton from England, who is now archdeacon of the church of Pamplona" (Roberto Ketenensi de Anglia, qui nunc Pampilonensis ecclesiae archidiaconus est).
In the preface to this translation, he explains that his interest is in geometry and astronomy, but that he is undertaking an astrological work for the sake of his friendship with Hermann.
[1] As late as 1143, Robert still had in mind his and Hermann's pet project of astronomical translations, for he wrote a letter to Peter the Venerable promising "a celestial gift which embraces within itself the whole of science … revealing most accurately, according to number, proportion and measure, all the celestial circles and their quantities, orders and conditions, and, finally, all the various movements of the stars, and their effects and natures.
Robert served King García Ramírez of Navarre (whose grandfather, Sancho Garcés, was lord of Uncastillo) as a diplomat, even drawing up the peace treaty signed with Raymond Berengar IV, regent of Aragon, on 1 July 1149.
[1] In 1151, Robert's bishop, Lope de Artajona, sent him as his delegate to a conference to resolve the disputed boundary between the dioceses of Pamplona and Zaragoza.
Charles Burnett notes that "Robert's education fit him well for the roles of diplomat, royal adviser and redactor of official documents.