A church will celebrate Mass as it would have been performed 600 years ago thanks to a partnership with the University of York.
PhD student Eleanor McCullough pieced together the Mass used in York churches in the 14th Century based on manuscripts from the period held by York Minster and the Bodleian Library.
It was used in a special ceremony last month at All Saints Church North Street, in York, to celebrate the Feast of Our Lady of North Street.
Eleanor McCullough, a PhD student in the Centre for Medieval Studies and holder of the All Saints North Street Fellowship, spent nine months researching the Mass.
She said: "Recreating the Mass was a complex task as in this period there were different elements for special feast days, and instructions for use were not always written down since priests were expected to know them.
“In addition, each diocese had its own special hymns and prayers for the feast days and sometimes only the opening lines were given so other sources had to be consulted to find the prayers in full.
“This may well be the first time that a York Lady Mass has been reconstructed and performed from the medieval manuscripts here in York since the Reformation."
In addition to the Mass, the research also uncovered plainchant that would have been sung in the same period and was performed by The Ebor Singers for the service.
All Saints Church will be holding a series of events on Saturday as part of the Festival of British Archaeology organised by The Council for British Archaeology.
All Saints North Street stands on a site used for worship for more than 1,100 years and contains one of the most important displays of medieval stained glass in the British Isles.