The large blue butterfly which became extinct in Britain in the 1970s is finally thriving again following decades of conservation efforts.

Although overall butterfly numbers have slumped across the country this year because of the wet weather, the Large Blue has bucked the trend with the highest numbers seen for at least 80 years.

If the surge continues, Britain’s most endangered butterfly could soon return to its pre-extinction peak and be removed from the International Union for the Conservation of Nature red list of threatened species. It is currently the only UK butterfly on the list.

Large blue numbers have soared in the south-west England, and around 60 per cent of the population now lives at Gloucestershire Wildlife Trust’s Daneway Banks and Somerset Wildlife Trust’s Green Down, where decades of grassland management has finally paid off.