Wild Things columnist Eric Brown describes recent discoveries which set pulses racing among butterfly enthusiasts and negative reaction from the leading butterfly protection charity.

Controversy disturbed the genteel world of butterfly-spotting after several very rare specimens appeared unexpectedly in south London.

Duke of Burgundy and Black-veined white butterflies were seen last month just a mile apart.

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Fewer than 20 colonies of the severely declining Duke are believed to survive in southern English woodlands and there are none around London. They lost vital habitat due to lack of coppicing. Originally known as Mr Vernon's small fritillary, the Duke requires specific habitat of rough, chalky grassland or woodland clearings with cowslips or primroses nearby on which the female lays eggs.

It has been declining in numbers since the 1950's and is now extinct in East Anglia and the Midlands. So reports of a couple found on the London-Surrey border sent shockwaves through butterfly circles.

Within weeks an even rarer butterfly turned up near the Duke sighting. The black-veined white was once fairly common in the New Forest, Kent, the Cotswolds and Forest of Dean but declared extinct as an English breeder when the final colony died out in Worcestershire in 1923.

Before then it had been regularly seen in east Kent with the county's last record in Herne Bay in 1922.

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Collectors were in a spin contemplating the return of black-veined white and a new colony of Dukes when Butterfly Conservation threw a spanner in the works. They issued a statement condemning what they called unauthorised introductions. BC backed sanctioned re-introductions involving the Large Blue and Chequered Skipper recently but insist unauthorised schemes are pointless.

They said:"BC is supportive of re-introductions when based on sound research necessary to ensure places the butterfly needs are suitable for long term survival of the species. These sightings are the result of an unofficial release and it is unlikely butterflies will survive to breed."

If this sounds stuffy then BC couldn't pour cold water on a third recent discovery. Swallowtails are Britain's largest and most spectacular butterfly. They are also among the rarest and confined mostly to East Anglian reedbeds. Some of the most dedicated entomologists have spent years trying to see one. My own experience is limited to observations in Bosnia when I marvelled at the sheer size of the insect. So when one turned up on a hilltop near Dover it set hearts fluttering and raised the question: is this another introduction, a cross-channel migrant or visitor from Norfolk. ? Paler markings seemed to indicate the butterfly was of continental origin and location supports the migration theory. Amazingly it was soon joined by a second swallowtail.

If all this wasn't enough to excite butterfly enthusiasts a species declared extinct in the 1960's was spotted on a Kent nature reserve. Large Tortoiseshell, with a wingspan of nearly three inches, died out as a result of Dutch Elm disease killing the trees they favoured for laying eggs on. Now it is back with no criticism yet from Butterfly Conservation.