Far out in the Channel, the lights of ships at anchor flickered while the lighthouse at Anvil Point emitted its steadier beam. Late on, a crescent moon shone a coppery orange.

But, undoubtedly, the most extraordinary light source to be seen was the vivid green gleam from the glow-worms that inhabit the herb-rich grassland on the cliffs and quarries in this tucked-away corner of southern Britain.

“It is a wonderful sight,” said Ben Cooke, the National Trust area ranger for Purbeck in Dorset, whose job includes monitoring the glow-worms and caring for their habitat.