Confidence: It's likely to be this, but I can't be certain.
Notes: I think this is a terrestrial amphipod of the family talitridae, closely related to the more familiar aqautic varieties. These have become very common in my back yard. There is no water for miles around. As far as I can gather at this stage, they are an accidental introduction from Australia.
Any info would be greatly appreciated. EG is there a native species to either Ireland or Britain?