use of runes on the coin may signify "continuing strong control by local leaders". The numismatist Marion Archibald notes that the issuing of "flattering" coins of this type, with the intention to win friends in Rome, probably indicated that as a sub-king, Æthelberht was assuming "a greater degree of independence than [Offa] was prepared to tolerate". The coins provide one of the few contemporary sources for Æthelberht. In March 2014 the fourth coin was discovered in Sussex by a metal detectorist. According to the British numismatist Rory Naismith, "Æthelberht’s coins could have been issued over a number of years, either during a spell when some or all of East Anglia asserted independence from Offa, or by some sort of arrangement to share minting rights with the Mercian ruler." Offa stopped Æthelberht from minting his own coins. In 793 the vulnerability of the English east coast was exposed when the monastery at Lindisfarne was looted by Vikings, and a year later Jarrow was also attacked, which the historian Steven Plunkett reasons would ensure that the East Anglians were "forced to seek firm leadership" in order to strengthen the region's defences. Æthelberht's claim to belong to the ruling Wuffingas dynasty, suggested by the use of a Roman she-wolf and the title REX on his coins, arose from the need for strong kingship in response to the Viking attacks. Death and canonisation Æthelberht was put to death by Offa under unclear circumstances, apparently at the royal vill at Sutton Walls. According to the Anglo-Saxon Chronicle, he was beheaded. Mediaeval sources tell how he was captured while visiting his future bride Ælfthyth and was then murdered and buried. In Richard of Cirencester's account, which cannot be substantiated, Offa's evil queen Cynethryth persuaded her husband to kill his guest, who was then bound and beheaded by a certain Grimbert, and his body disposed of. The mediaeval historian John Brompton's Chronicon describes how the king's detached head fell off a cart into a ditch where it was found, before it restored a blind man's sight. According to the Chronicon, Ælfthyth became a recluse at Crowland and her remorseful father founded monasteries, gave land to the Church and travelled on a pilgrimage to Rome. The execution of an Anglo-Saxon king on the orders of another ruler was very rare, although criminals were hanged and beheaded, as has been discovered at Sutton Hoo. Æthelberht's death made the possibility