The evening service of Vespers dates back to the earliest days of the Divine Office of the Roman church. In churches it traditionally began with the versicle and response Deus in adjutorium, followed by five psalms, each preceded and followed by an antiphon. As well as readings and prayers the service would also include a hymn and the singing of the Magnificat. Polyphonic settings of the psalms and Magnificat were common from mediaeval times, and in princely chapels or on solemn feastdays these settings could be quite elaborate. (The antiphons would normally have been sung to plainsong.) In 1610 Monteverdi was 43 and working under difficult conditions as a composer of theatrical and other secular music at the Court of the Duke of Mantua. He had published no liturgical music since his teens, but it seems likely that with the recent death of his wife and his own ill-health he was anxious to obtain the security of a church appointment. The collection of pieces from which the work now known as the "Monteverdi Vespers" is drawn, was published in Venice in that year and may have helped him to secure the post of "maestro di capella" at St. Mark’s, Venice when the incumbent, Giovanni Gabrieli, died in 1612. It also contains the Mass "In illo tempore" which seems to have been composed with the aim of securing the patronage of Pope Paul VI (to whom the collection as a whole was dedicated) and two Magnificats, clearly to be regarded as alternatives to one another. There has been considerable controversy over whether the Vespers music in the collection was intended to be sung as a single work and if so, in what order. The original title page, referring (in addition to the Mass and the music for the Vespers of the Blessed Virgin) to other "sacred concerti suitable for the chapels or private apartments of Princes" does not clarify the matter. The non-liturgical "sacred concerti" are Nigra sum (solo), Pulchra es (duet), Duo Seraphim (trio), Audi coelum (duet plus chorus) and Sonata sopra Sancta Maria (single voice line plus instruments). The majority of expert opinion favours these items being performed in the order in which they appear in the original printed collection, i.e. one between each of the choral vesper psalm settings and the Sonata preceding Ave Maria Stella. This is on the grounds that they were intended as substitutes for the plainsong antiphons that would otherwise have been necessary in a liturgical context. It is a solution which works well in performance, providing variety and contrast, though it does involve one or two rather awkward key sequences (e.g. between Audi coelum and Lauda, Jerusalem). The other main difficulty with the Vespers is what instrumentation to use and what division between solo and tutti. The original edition, printed long before the age of the modern "full score", gives a fair amount of guidance but is far from conclusive. Though written with small professional forces in mind, probably with one player to a part and soloists drawn from the choir, it is known that festal performances in St. Mark’s, Venice were very spectacular and made full use of the spatial effects that could be obtained by distributing the performers around the building. If, as is thought by some, Monteverdi used the Vespers as his test piece prior to appointment at St. Mark’s , then some fifty or so performers could have been involved. Commonsense suggests adaptation to circumstances. Our performance takes place in a larger and more reverberant building than early performances would have done and uses a much larger choir. Some strengthening of the orchestra is therefore needed. Guildford Cathedral acoustics and the size of the choir are also the main justification offered for the perhaps more controversial use of modern rather than "authentic" early 17th century string and brass instruments. In the 1610 publication, Monteverdi employs all the styles of church music and technical devices known in his day – traditional polyphony, the new monodic style developed mainly in secular music, divided choirs and echo effects, exploitation of instrumental tone colour, "falso bordone" or the chanting of psalms. Binding the whole together is the inventive use of the appropriate plainsong psalm-tone as cantus firmus in each of the five psalms and in the Magnificat.