Monteverdi's Vespers (1610) is a musicological mystery. Was this vast compendium intended for complete performance? In what order was it supposed to come? And how did the erotic poetry from the Song of Songs end up in a work of Marian devotion? Practically the only thing we know about it for certain is that it is 400 years old, which was good enough reason for the York Early Music festival to commence with a series of concerts exploring the enigma.

The main obstacle to presenting the Vespers in its entirety is that it runs the risk of the performers being there all night; and the Yorkshire Baroque Soloists very nearly were, with a marathon in the Minster that concluded just shy of midnight.

Peter Seymour's approach was to stage a liturgical reconstruction in the nave, complete with clouds of incense and the Cantors of Ampleforth Abbey providing the plainchant. It was followed by a late-night recital of the more intimate pieces in the Chapter House, which seemed a fine solution – like having the main feature on DVD, with outtakes and alternate scenes as optional extras.

Some light relief came in the form of I Fagiolini's L'Amfiparnaso, a burlesque based on the characters of the commedia dell'arte by Orazio Vecchi (1550-1605). His unusual works have been dubbed "madrigal comedies", but according to I Fagiolini's director Robert Hollingworth they are more akin to a Renaissance edition of the Fast Show in which the characters come on, deliver their catchphrases and leave.

Yet in among the flatulence jokes and unrestrained use of a genuine slap stick were pauses for some sublime, harmonic meditations the expressive equal of anything the northern Italian madrigal tradition has to offer.

York Early Music festival continues until 17 July. Box office: 01904 658338.