The manuscripts are mostly on religious subjects, although the Islamic Arabic ones include philology, literature and science. The Islamic manuscripts include fragments of Kufic Qur'ans, Qur'an commentaries, Hadith, law, and mysticism. The Syriac manuscripts include works on church documents, gospels, works on liturgy, lives of saints and homilies. Among the earliest Syriac items are a number of important fragments originating from St. Catherine's Monastery, Sinai. The Arabic Christian ones include a fragment of the oldest known text of the Acta Thomae, and a very early copy of works by St. Ephrem.
The Christian manuscripts are important for Christian Theology, Church History in general, and the history of Eastern Christianity in particular. This collection includes the largest collection of Christian Arabic manuscripts in Europe after the Vatican and the Bibliotheque Nationale. The Islamic collection is the third largest Arabic manuscript collection in the UK. It is included in Brockelmann's Geschichte der Arabischen Literatur (GAL).