The UK's second largest butterfly has "officially" returned to Norfolk after nearly half a century, experts have confirmed.

The purple emperor was declared extinct in the county in the early 1970s and has declined by 31% across the UK in the last 10 years.

"Thanks to... changes to the way we manage our woodlands, we’re once again creating the type of habitat this butterfly needs to survive," Kiri Stuart-Clarke, from Butterfly Conservation, said.

The last known breeding colony in the county was at Foxley Woods, near Bawdeswell - but in recent years it has been consistently recorded near the coast in places like Sheringham Park and Beeston Common.

It has a wingspan of up to 8.4cm (3.3in) - second only in size to Norfolk's resident swallowtail butterfly.