At the latest, Æthelberht must have converted before 601, since that year Gregory wrote to him as a Christian king. An old tradition records that Æthelberht converted on 1 June, in the summer of the year that Augustine arrived. Through Æthelberht's influence Sæberht, king of Essex, also was converted, but there were limits to the effectiveness of the mission. The entire Kentish court did not convert: Eadbald, Æthelberht's son and heir, was a pagan at his accession. Rædwald, king of East Anglia, was only partly converted (apparently while at Æthelberht's court) and retained a pagan shrine next to the new Christian altar. Augustine also was unsuccessful in gaining the allegiance of the British clergy.