It’s unmistakable: a Swallowtail Butterfly:
It’s taken us ages to get this close. It’s hot and the butterfly is very active. Here it is in Reverend Francis Orpen Morris’s The History of British Butterflies from 1853:
This one is busy laying eggs:
It looks like the alien creature it is from this angle.
The Swallowtail is the largest of the UK’s native butterflies, and also one of the rarest. In 1853 Rev. Morris says it has been found in Yorkshire, Dorset, Hampshire, Middlesex, Sussex, Essex, Kent, Norfolk… “But most of all in Cambridgeshire and Huntingdonshire, where, in the fenny districts, it has been, and even is still, very abundant; though, as those parts are fast being drained, it is feared that in time we may lose this most conspicuous ornament of our cabinets.”
Many things have changed since 1853. We now use commas less frequently than the Reverend Morris did. The UK variety of the Swallowtail butterfly is also now only found in the fens of the Norfolk Broads in a small area of East Norfolk. I’ve never been there and I’ve never seen one.
Here it is in my 1939 copy of Edmund Sandars’s classic A Butterfly Book for the Pocket:
Back in 1939 he wrote: “The butterfly was at one time commoner than it is now, and has been recorded in most of the southern counties. But for many years it has been restricted to the habitat described.”
I’m in Italy. The Swallowtail is common here.