"I believe this is a nymph (immature) of a stilt bug. Key characters are that all the legs are long where grasshopper and cricket nymphs have longer hind legs; the shape of the head/eyes and lack of a shield-like pronotum, and the antennae which appear to be either short or to have a long, solid first segment as opposed to other small green nymphs with flexible multi-segmented antennae."

Thanks to Jennie for the identification.
Mr PGC