It slowly recovered, and the very mild English winters of the Nineties - including the one just over - have quickened the pace. Surveys by the Royal Society for the Protection of Birds and English Nature, the Government's wildlife conservation arm, have found the pairs rising from 900 in 1990 to 1,670 now.
Their range has spread from three southern counties at the low point of the early Sixties to seven. The Dartford Warbler lives in heather and gorse, hunting insects and spiders. The destruction of England's lowland heaths bears much of the blame for its decline.
A warming climate may have favoured the warbler and boost the British fortunes of the Cetti's Warbler, a recent colonist from southern Europe. But the Royal Society for the Protection of Birds would much rather pollution was not allowed to turn up the planetary thermostat.
If, as climatologists forecast, average temperatures are set to rise more rapidly than at any time in the past 10,000 years, there will be rather more losers than winners in nature. The society, which has some 600,000 members, is sending a delegation to the UN Climate Change conference which ends next Friday.
Its scientists say wildlife on Britain's highest mountain tops will be most at risk. As the nation warms, these lofty refuges for sub-Arctic lifeforms will be erased by creeping mildness. They cannot climb higher because they are already at or near the summit.
The cloudberry needs five months of frost to stimulate the growth of its seeds - important food for mountain birds such as the dotterel, ptarmigan and snow bunting.
The society is also worried about the salt marshes and mudflats which are feeding grounds for millions of waterfowl, ducks and waders being lost due to rising sea levels.
In Berlin, meanwhile, the UN climate change conference has got off to a painfully slow start. Ministers from 60 nations arrive midweek for the final three days, when there is likely to be a great deal of hard negotiating left for them to oversee. There is a growing likelihood that neither developed nor developing nations will make any commitments to stabilise or reduce rising emissions of greenhouse gases.
The Dartford Warbler is so called because the first specimens to be described by ornithologists were shot near Dartford, Kent, in 1773. It has been extinct in that county since 1891.Reuse content