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Looks like Rough Periwinkle - they come in a range of colours, even banded.
Definitely not a Dog Whelk.
I am embroiled in difficulty here
See also here -
THREE MARINE PROJECTS
Thank you. Thanks for the links too.
...when getting pics of shells try to get an opening pic as well as this really helps ID of sp. They don't mind really as long as you put them back where they came from and in the same position. There are 3 types of rough Periwinkle and to be definitive you need the opening pics, even this may not be enough. Sometimes you need to find the male to look at genitalia - that isn't fun for the winkle (don't recommend going this far).
...to edit & move to invertebrates :)
Thank you. Will do.
Lat/Lng: 50.2897, -3.8943
OS grid ref: SX651450