Magpie is not in Dave's songbook, and I am unfamiliar with it. A number of his songs are in a songbook he published, and sells at the concerts, including "Blackbird", words above, and "Bonnet and Shawl" and whatever that one is called that starts "My father gave I watch and chain..." about going off to war to fight, and a sad/clever one called "the Fox" and told from the foxes p.o.v.
Blessings,
Barbara