A worldwide community photographing and learning about wildlife
Graphium milon
Sorry to throw a spanner in the works.
These two very similar species were once considered subspecies.
G. milon has a thinner blue zone and darker black zones. The butterfly is slightly larger than the common bluebottle. Compare these two and decide which you think best matches your spotting.
http://lepidoptera.pro/taxonomy/15214
http://lepidoptera.pro/taxonomy/15126