A butterfly has returned to Norfolk's largest ancient woodland, 50 years after it was declared extinct in the county.

It's the first sighting of the purple emperor in Norfolk Wildlife Trust's (NWT) Foxley Wood since the 1970s, following a handful of sightings over the last few years in Sheringham Park.

This confirmed sighting by Butterfly Conservation in Mid Norfolk not only heralds a successful restoration, but it adds weight to the belief the butterfly is potentially breeding again in Norfolk.

The trust's head of nature reserves John Milton said: "This is extremely exciting and rewarding news. Despite nearly 30 years as a conifer plantation, the restoration of Foxley Wood has made it hospitable again for this impressive butterfly.

"Purple emperors spend much of their time in the high woodland canopy, making observation difficult, but the iridescent purple males descend to take salts.

"As with the silver-washed fritillary butterfly, success for the purple emperor requires a precise habitat. A good supply of shaded sallow trees is essential for egg laying and the best sites invariably feature mature oak trees."

Foxley Wood was the breeding stronghold for purple emperors, before large parts of the wood was converted to a conifer plantation in the 1960s. The felling of large oaks triggered the decline and disappearance of the butterfly.

The wood's fortunes changed for the better when it was acquired by the trust in 1988 and the ancient woodland habitat restored. The varied habitats and rich biodiversity mean it's again a haven for butterflies.

An expanding population can re-colonise new sites, but only if the perfect habitat is available.

For many, the gentle beauty of butterflies fluttering from one flower to another is the joy of summer, but they can also tell us much about the health of our countryside.

NWT is working on a landscape scale across the county to create healthy habitat for wildlife.

Mr Milton added: "We've restored Foxley Wood by putting it back to deciduous woodland but it remains in isolation. The real challenge - and it's somewhat visionary - is to connect it through corridors in the landscape with other ancient woods in north Norfolk."