Urban's principal monument is the dossier he created to sustain the great cause he began in 1119 against the neighbouring dioceses of Hereford and St Davids, the Book of Llandaff, which was compiled between 1120 and 1134. He used as his primary source a large cache of early diplomas and charters relating to the episcopal communities of south east Wales, some dating back to the sub-Roman period. He or his clerks deliberately edited these to present a fictitious continuity of bishops of Llandaff from the sixth century onwards, back to the times of St Teilo, the original patron of the Llandaff community.
Urban's principal monument is the document he created to support his great cause, which began in 1119 against the neighboring dioceses of Hereford and St Davids, the Book of Llandaff, compiled between 1120 and 1134. He used as his primary source a large collection of early diplomas and charters relating to the episcopal communities of southeast Wales, some dating back to the sub-Roman period. He or his clerks deliberately edited these to present a fictitious continuity of bishops of Llandaff from the sixth century onwards, back to the times of St Teilo, the original patron of the Llandaff community.