Britain's rarest butterflies have enjoyed a boom in numbers as conservationists say the 2018 heatwave led to a record year for some species

More than two thirds of British butterfly species were seen in greater numbers than in 2017, according to the annual UK butterfly monitoring scheme.

Among them is the large blue butterfly - which was extinct in the 1970s but has now returned in greater abundance than at any time since records began in 1976.

Large blues returned to the countryside of south-west England following intensive conservation efforts and were found to have increased in number by 58% in 2017.

No estimated numbers were provided in the research, but separate figures from June and July last year recorded around 5,700 large blues at Collard Hill, near Glastonbury, alone.

Professor Tom Brereton, at Butterfly Conservation, which helps run the scheme, said: “Large blues are one of the most successful examples of conservation in a way, it’s a flagship species.”

Another rare butterfly, the black hairstreak, enjoyed a record year in 2018 - swelling in number by more than 900% compared to 2017 on the scheme’s annual measure of abundance .

Professor Brereton added: “It was a really nice sunny and dry period when those butterflies were completing their development in the immature stages.