The article examines a medieval psalter conserved under number 54 at the municipal multimedia library Médiathèque de Cambrai (Cambrai, France). It is noted that the manuscript contains 103 parchment sheets, which also includes prayers and a calendar containing 43 obituaries, referred to as the necrology of Florennes (Belgium). It is suggested that the psalter belonged to 11th century Bishop Gérard I de Cambrai. The author describes the manuscript and its content, particularly its calendar, and offers additional arguments advancing the psalter's rightful ownership. Gérard's origins, his influence and political engagement, and the political history of localities in France, Belgium, the Netherlands, and Germany during the 10th and 11th centuries are also discussed.