Crickets found in Wales?
There are crickets species living in Wales (Reference)

Field Grasshopper

Green Grasshopper

Meadow Grasshopper

Roesel's Bush-cricket

Oak Bush-cricket

Speckled Bush-cricket

Mottled Grasshopper
and even if a species is not common in this part of the UK it might be brought there e.g. as a secret passanger in a car.