Eariler answers on this subject were:
Well the ancient Britons stained their skins with woad and had the images of animals etched on to their bodies, so maybe it originated there. If you want to know anything about the tattooing, visit www.tattoo.co.uk which has the history, too.
Submitted by: johnjo
My thoughts are that it was worn by sailors as a sign of returning home (the swallow being migatory and returning to Britain each year.
Submitted by: sammyBoy
This was a popular tattoo with sailors who used it for good luck - on a long voyage the sight of a bird meant land was nearby.
Submitted by: woolley