The Chronicon ex chronicis is a world wide history which begins with the creation and ends in 1140. The chronological framework of the Chronicon was presented by the chronicle of Marianus Scotus (d. 1082). A great deal of additional material, particularly relating to English history, was grafted onto it.
The greater part of the work, up to 1117 or 1118, was formerly attributed to the man Florence of Worcester on the basis of the entry for his death under the annal of 1118, which credits his skill and industry for making the chronicle such a prominent work. In this view, the other Worcester monk, John, merely wrote the final part of the work. However, there are two main objections against the ascription to Florence. First, there is no change of style in the Chronicon after Florence's death, and second, certain sections before 1118 rely to some extent on the Historia novorum of Eadmer of Canterbury, which was completed sometime in 1121 - 1124.
The prevalent view today is that John of Worcester was the principal author and compiler. He is explicitly named as the author of two entries for 1128 and 1138, and two manuscripts (CCC MS 157 and the chronicula) were written in his hand. He was seen working on it at the behest of Wulfstan, bishop of Worcester, when the Anglo-Norman chronicler Orderic Vitalis visited Worcester:
|Ioannes Wigornensis a puero monachus, natione Anglicus, moribus et eruditione uenerandus, in his quæ Mariani Scotti cronicis adiecit, de rege Guillelmo et de rebus quæ sub eo uel sub filiis eius Guillelmo Rufo et Henrico usque hodie contigerunt honeste deprompsit. [...] Quem prosecutus Iohannes acta fere centum annorum contexuit, iussuque uenerabilis Wlfstani pontificis et monachi supradictis cronicis inseruit in quibus multa de Romanis et Francis et Alemannis aliisque gentibus quæ agnouit [...].||"John, an Englishman by birth who entered the monastery of Worcester as a boy and won great repute for his learning and piety, continued the chronicle of Marianus Scotus and carefully recorded the events of William's reign and of his sons William Rufus and Henry up to the present. [...] John, at the command of the venerable Wulfstan bishop and monk [d. 1095], added to these chronicles [i.e. of Marianus Scotus] events of about a hundred years, by inserting a brief and valuable summary of many deeds of the Romans and Franks, Germans and other peoples whom he knew [...]."|
The Chronicon survives in five manuscripts (and a fragment on a single leaf):
In addition, there is the chronicula, a minor chronicle based on the Chronicon proper: MS 503 (Dublin, Trinity College), written by John up to 1123.
For the body of material dealing with early English history, John is believed to have used a number of sources, some of which are now lost: