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They were looking for caterpillars of the UK's five species of hairstreak butterfly.

The spokesperson said the Sheffield tree was "fortunately resistant" to the disease and was also home to the white-letter hairstreak butterfly, which had saved it from the chop during Sheffield City Council's felling programme.

The white-letter hairstreak’s northward journey is thought to be a response to the warming climate.

In Northern Ireland and the Isle of Man similar measures are in place to protect species, including the dingy skipper and the purple hairstreak.

Thought to be about 120 years old, that elm has won a stay of execution, but only because it is home to a rare species of butterfly, the white-letter hairstreak.