The book was first published in London in 1596, while my copy is a reprint published in Frankfurt in 1601.
It is a collection of chronicles and histories of England written after Bede's Ecclesiastical History, and includes the following items:
William of Malmesbury, Gesta regum Anglorum;
William of Malmesbury, Historia Novella;
William of Malmesbury, Gesta pontificum Anglorum (first four books of five);
Henry of Huntingdon, Historia Anglorum;
Roger of Howden, Annales;
Æthelweard, Chronicon;
Ingulf of Croyland, Historia monasterii Croylandensis.
These are all editiones principes of these works. The manuscript uniquely preserving Æthelweard's Chronicon, BL Cotton Otho A.x, was mostly destroyed in the fire at the Cotton Library in 1731, and the preservation of its text chiefly owes to this edition.
The editor, Sir Henry Savile (1549-1622), was a mathematician and classical scholar, and was one of the main translators of the King James Version. He is also known as an translator of Tacitus's Germania and Agricola and also as the editor of works of John Chrysostom. He founded the positions of Savilian Professors of Astronomy and of Geometry at the University of Oxford in 1619.