Confidence: I'm as sure as I can be.
Notes: Assuming that this was found around Scarborough its highly unlikely to be Patella depressa, a southern species thats not recorded from the North Sea and only gets up the Irish Sea as far as mid-north Wales. Some Patella vulgata can have a dark foot, perhaps depending on their diet but they never have the chalky white mantle tentacles of P.depressa. Furthermore, on the images the back end of the shell doesn't have the sightly "squared off" appearance of P.depressa. The tortoiseshell-brown colour of parts of the shell is characteristic of P.v.