Strathearn Valley, Scotland ~ Strathearn is the strath (a large river valley) of the River Earn, in Scotland. It extends from Loch Earn in Perth and Kinross to the River Tay. The royal dukedom of Strathearn has occasionally been awarded to members of the British Royal Family. Prince William was created Earl of Strathearn, as a subsidiary title to Duke of Cambridge, on 29 April 2011, the day of his wedding to Catherine Middleton.