DISCOVER Portland’s rare Blue butterflies.

Living on the limestone of old quarries and finding seclusion in the derelict High Angle gun battery, a sub-species of the Silver-studded Blue can be spotted.

The males are bright blue, have narrow dark boarders to their upper side, and the hind wing has distinct marginal spots. All of these make it very easily recognisable.

The butterfly is almost certainly a threatened species, and can only be found in very few places in the south of England, so if you do spot one, be careful not to cause them any harm.

Here you can also explore the old battery tunnels, though if you do decide to do this you will need to be extra careful.

The whole Verne Citadel, which includes the gun battery, is also a scheduled monument under the Ancient Monuments and Archaeological Areas Act 1979 as a place of national importance and is Grade II listed.

Having a short life, the battery was abandoned in 1907, but served as an arms hold at the end of the First World War. It had a short rebirth in the Second World War as an anti-aircraft battery whilst storing ammunition ready for the D-Day landings in 1944.