For anybody wishing to check, https://en.wikipedia.org/wiki/List_of_Outer_Hebrides says, "There are other outliers with cultural links to the Outer Hebrides that are not part of the archipelago itself. These include the St Kilda group, which are quite distinct geologically and no longer inhabited, Sula Sgeir and North Rona to the north and isolated Rockall, which is 367 kilometres (228 mi) to the west of North Uist."