Some of Britain’s most threatened butterflies appear to be showing signs of recovery after decades of decline, experts say.

A monitoring programme run by Butterfly Conservation and the Centre for Ecology and Hydrology saw rare species including the wood white and the marsh fritillary record large increases last year.

Experts said the improvement in the butterflies’ fortunes was likely to be the result of targeted conservation action – and better weather in 2010 than the past few years.

But one of the UK’s rarest butterflies, the Lulworth skipper, which is confined to the Dorset coast, had its worst year since the monitoring scheme began in 1976, and there are concerns that managing landscapes to benefit other species may be harming the skipper.

Meadow browns, one of the country’s most common species, also had its worst year on record, while Essex skippers, small skippers and wall butterflies also fared badly.

Butterfly Conservation said overall butterfly numbers continued to decline, with three quarters of the nearly 60 species found here seeing numbers fall in recent decades and nearly half of them seriously threatened.

Most of the at-risk species are in long-term decline, but three quarters of the threatened species did see an increase in numbers in 2010 on 2009 levels.

The wood white, which has suffered a 96 per cent decline since the 1970s, saw numbers increase last year by 600 per cent, while the marsh fritillary, in decline since the 1950s, more than doubled its numbers from 2009 to 2010.

Tom Brereton, head of monitoring at Butterfly Conservation, said the increase in “specialist” species which rely on a particular habitat showed that conservation efforts to restore those areas were helping - once the species had good weather.

Butterflies were badly hit by three poor summers before better weather last year, while a cold winter in 2009/2010 will have helped check parasites and stop butterflies emerging too early, helping the insects breed successfully.