Bede has often been accused of a hostile or ungenerous attitude towards the British church (which may roughly be said to comprise the Britons of Wales, Cornwall and Cumbria-Strathclyde). And it is true that hard sayings are to be found in the Historia Ecclesiastica.1 Failure to convert, or even try to convert, the invading Anglo-Saxons is only part of the story.2 Another element, to be considered here, lies in the calculation of Easter.3 In 716 the last of the Irish communities, Iona, had conformed to the Roman practice, but the Britons did not follow suit until 768, so that in Bede‘s experience there was a substantial body of believers who disagreed not over the major issues of faith and doctrine but, principally, about the date of Easter and how to find it. Bede‘s tribute to Aidan, a disciple of Iona who died in 651, is somewhat marred by a reference to this problem.4 Why, after eighty years, should it still rankle? I shall suggest that the Britons were felt to be wrong-headed because, among other things, they were ignoring an observable fact.