This paper is offered in the hope that it will provide reliable evidence for those wishing to make use of episcopal dates during the century 850–950. The original editors of the Handbook of British Chronology were assured by experts that ‘until all the available charter-evidence had been critically sifted, it would be useless to try and revise the available lists of Anglo-Saxon bishops’, so they used for their lists the information available in W. Stubbs's Registrum Sacrum Anglicanum, 2nd ed. (Oxford, 1897) and W. G. Searle's Anglo-Saxon Bishops, Kings and Nobles (Cambridge, 1899). We are still far from the desired state of charter study, but a good deal has been done on this and related studies in the last few decades, and perhaps the time has come to look again at the bishops' dates. In many cases the episcopal witnesses can corroborate or impugn the genuineness of a charter, and it is sometimes the misfortune of the Anglo-Saxon historian, in using the appearance of a certain bishop to strengthen the validity of a charter, to find that the date of the bishop's episcopate is determined by the very charter in question. So the critical sifting of all the available charter evidence must include a study of episcopal dates – one cannot take place without the other.