"Hello Mr Magpie!" I whispered, as I reached the north eastern sector of Clissold Park. Why do I do this? I used to think it was kind of commercial TV brainwashing from the 1970s kids show (Magpie was presented by ex-hippies). But apparently it goes back even further than the 70s, to our fear of the devil or some celtic deity.
Some interpretations of the myth
However, I'm convinced that it's something to do with leprechauns.