A blue female calliphorid fly from our summer holiday in 2010: possibly Protocalliphora azurea (Diptera: Calliphoridae) but I always find the identification of these blue Calliphorids very difficult. Roger Thomason suggested P. azurea here. but all the photos on the web seem to show the females as distinctly greenish (though the males are bluer).
Susan R. Walter has some useful tips on distinguishing Protocalliphora from the similar Protophormia here.
Photo taken in Bousdale, near Guisborough, North Yorkshire, UK, on 2010-08-08.