Old Dart

Origin: Possibly from the river Dart in Devonshire which enters the sea at Dartmouth, location of a Royal Navy College. Royal Navy officers who were returning to England at the end of a foreign tour of duty referred to going back to the "Old Dart" for further training. Alternatively a variation of "old dirt" (compare old sod). Origin information sourced from Wiktionary contributors (CC BY-SA 4.0).