In 9th-century Mercia and Kent, royal charters were produced by religious houses, each with its own style, but in Wessex there was a single royal diplomatic tradition, probably by a single agency acting for the king. This may have originated in Egbert's reign, and it becomes clear in the 840s, when Æthelwulf had a Frankish secretary called Felix. There were strong contacts between the West Saxon and Carolingian courts. The Annals of St Bertin took particular interest in Viking attacks on Britain, and in 852 Lupus, the Abbot of Ferrières and a protégé of Charles the Bald, wrote to Æthelwulf congratulating him on his victory over the Vikings and requesting a gift of lead to cover his church roof. Lupus also wrote to his "most beloved friend" Felix, asking him to manage the transport of the lead. Unlike Canterbury and the south-east, Wessex did not see a sharp decline in the standard of Latin in charters in the mid-9th century, and this may have been partly due to Felix and his continental contacts. Lupus thought that Felix had great influence over the King. Charters were mainly issued from royal estates in counties which were the heartland of ancient Wessex, namely Hampshire, Somerset, Wiltshire and Dorset, with a few in Kent.