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I think this one is the shore crab Sara, Carcinus maenas.
It was pretty big, and quite orange in colour (though it doesn't show well in the photo)
Sara Garcia Hipolito
The shape does look more like a Shore crab, but it was very large (aprox. 7cm). The colour was also more like an Edible Crab. But since yourself and 3 epople agree on it being a Shore Crab, and they probably have a lot more practice than me at identifying crabs, I have reviewed my ID
It has an orange hue to it, shore crabs are variable to a degree when adults, much more so as juveniles. The size is reasonably large also for a shore crab but not oversize. Edibles can an awful lot bigger, they can weigh 7lbs, maybe even more whereas a shore crab of 8oz would be a big one. The shape is the key IDing feature, the carapace on an edible crab is a quite long oval shape and as Trudy says appears like a pie crust around the edges, shore crab has a serrated edge to the carapace.
Lat/Lng: 54.3138, -8.5678
OS grid ref: NU731108