Anglo-Scottish border English king, Edgar the Peaceful, at his council in Chester. After Kenneth had reportedly done homage, Edgar rewarded Kenneth by granting him Lothian. Despite this transaction, the control of Lothian was not finally settled and the region was taken by the Scots at the Battle of Carham in 1018 and the River Tweed became the "de facto" Anglo-Scottish border. The Solway–Tweed line was legally established in 1237 by the Treaty of York between England and Scotland. It remains the border today, with the exception of the Debatable Lands, north of Carlisle, and a small area around Berwick-upon-Tweed, which was taken
England–Wales border 1972. Whether Monmouthshire was part of Wales, or an English county treated for most purposes as though it were Welsh, was also settled by the 1972 Act, which included it in Wales. The modern boundary between Wales and England runs from the salt marshes of the Dee estuary adjoining the Wirral Peninsula, across reclaimed land to the River Dee at Saltney just west of Chester. It then loops south to include within England an area southwest of Chester, before rejoining the Dee, and then loops east of the river to include within Wales a large area known as Maelor, formerly