Auchenorrhyncha are the leafhoppers, planthoppers, cicadas and allies. Some authorities divide this into two separate sub-orders: Cicadamorpha and Fulgoromorpha. Many have enlarged back legs and can jump. [Nature Spot].
A leafhopper is the common name for any species from the family Cicadellidae. These minute insects, colloquially known as hoppers, are plant feeders that suck plant sap from grass, shrubs, or trees. Their hind legs are modified for jumping, and are covered with hairs that facilitate the spreading of a secretion over their bodies that acts as a water repellent and carrier of pheromones. [Wiki].
ROSE LEAF HOPPER : Edwardsiana rosae
The leafhoppers are a family (Cicadellidae) of sap sucking true bugs, there are more than 180 species found in Britain. They can jump or fly short distances and most do not feed on or cause noticeable damage to garden plants.
Rose leafhopper feeds on the leaves of roses and some other rosaceous trees and shrubs such as hawthorn and rowan. They readily jump away if disturbed and can cause a mottling on leaves of affected plants, especially those in hot dry situations. They are seldom noticed of any plants but roses in Britain and often do not affect the vigour of garden plants.. [RHS].
A small inconspciuous silvery spot on a fern.
Look closer and you will see that it has legs ready to jump. Note too that its wings are minute. They have hardly started to grow so this is a young one.
NATURE SPOT : https://www.naturespot.org.uk/family/cicadellidae
WIKIPEDIA : https://en.wikipedia.org/wiki/Leafhopper