In the late eighth and ninth centuries the only denomination of coin produced in southern England was the silver penny. As of 2007, 152 coins of Æthelred struck by 32 different moneyers have been recorded. His reign is described by the numismatists Adrian Lyons and William Mackay as "a critical point in the development of the English coinage". His first Four Line issue was stylistically similar to the Floriate Cross penny of his predecessor, Æthelberht, but he soon abandoned this and adopted the design of his Mercian brother-in-law, Burgred, resulting in a common coinage design across southern England for the first time. The historian and numismatist Rory Naismith comments that Æthelred