Franco-Roman antiphonary with material for the whole liturgical year (ff. 6r-240v), including part of a tonary (ff. 235r-241v), and a fragment of Old Hispanic antiphonary (ff. 1r-v and 3v) with material that in other Old Hispanic manuscripts is assigned for quotidian Sundays (e.g. E-L Ms 8, f. 281v onwards); ff. 2r-v, 3r and 4r-5v also seem to be misplaced or flyleaves extracted from a book very similar to the Franco-Roman antiphonary (same handwriting, notation and ruling of the parchment. Note that antiphonaries in the Old Hispanic rite have chants for the cathedral ordo (i.e. vespers, matutinum and mass, and, on penitential days only, also the hours of tertia, sexta and nona), while antiphonaries in the Franco-Roman rite contain the chants for all office hours (monastic ordo, i.e. all services except the mass). The sequences in f. 2r have been identified as 'Old Hispanic' (e.g. in Fernández de la Cuesta, 1985, p. XIX). However, the lack of cognates in any other Old Hispanic manuscript (Códice Álvaro is given by Fernández de la Cuesta, as an Old Hispanic manuscript with a cognate, but this manuscript, in fact, does not contain any other Old Hispanic material, so its sequence might be a Roman accretion), the liturgical assignments of these sequences ('de uno iusto' and 'de sanctis' in contrast with the Old Hispanic quotidian material in ff. 1r-v and 3v) and the codicology of this manuscript puts into question this identification. Before the current binding of GB-Lbl Add MS 30850, its fragment of Old Hispanic antiphonary in all likelihood served as the flyleaves of the Franco-Roman antiphonary, perhaps at its end. Maybe ff. 1r-v and 3r-v belonged to the same sheet 1r (hair) - 1v (skin) - 3v (skin) - 3r (hair); the last of these folios belongs to the Franco-Roman antiphonary, very likely recycling a blank page of the flyleaves. Drawings added to these folios also link them (and perhaps 5v too).
Notation: previous authors regard the notation of the main, Franco-Roman rite, part of this manuscript as 'Visigothic', i.e. Old Hispanic (see, e.g., Fernández de la Cuesta, 1985, p. X). However, several of its neumes do not exist in any Old Hispanic chant manuscript, e.g. its trigon or many of its compound neumes starting with a climacus. It is more accurate to call the notation of the main part of this manuscript Catalan notation. The fragment of Old Hispanic manuscript has no trace of having born any kind of Old Hispanic notation. Later hands added Aquitanian notation to some words of ff. 1r-v, and the melodic contours that they create are not alike those in any cognate of the Old Hispanic chants transmitted in this fragment - the Aquitanian neumes were very likely added informally as seems to be the case of the drawings in these folios. In f. 3v a few chants also have Aquitanian neumes in some of their syllables as well as Catalan neumes, just as those in the main, Franco-Roman, part of this manuscript. These neumes, as those in ff. 1r-v might have been added later and informally - their melodic contour is nothing alike that of the cognates of these chants in the Old Hispanic rite manuscripts.
Date: because its main section contains Roman liturgy and Old-Hispanic-like notation (which I noted is really closer to Catalan notation), previous scholars have proposed a copy-date very close to the official suppression of the Old Hispanic rite in the Iberian Península (i.e. after the Council of Burgos, 1080/1). Fernández de la Cuesta, 1985, p. XV, places its copy-date between 1081, i.e. after the council of Burgos, and 1088, i.e. before the consecration of the altar for Santo Domingo de Silos at the church of the abbey of Santo Domingo de Silos (which is the ascribed provenance of this manuscript), because this manuscript does not have a proper office for this saint.
Provenance: the whole codex is ascribed to the abbey of Santo Domingo de Silos because it was preserved there from the middle ages (see Boylan, 1992, pp. 69, 71-2) until it was sold to UK owners in the nineteenth century.
Liturgical tradition: unknown because it lacks Old Hispanic musical notation.
Randel responsorial tone tradition: unknown because it lacks Old Hispanic musical notation.