Oddly I don't have any British magpie haiku despite numerous sightings over the years.
Although I do have a magpie-lark (aka mudpie lark) haiku during my years living in Queensland, Australia.
christmas morning heat –
two fledgling mudpie larks
Publications credits: Blithe Spirit Vol. 7 No. 1 Feb 1997 (British Haiku Society); sundog haiku journal: an australian year sunfast press 1997 reprinted 1998 California State Library – Main Catalog Call Number : HAIKU S852su 1997; de facto 2 issue 2. (2008)