The terms and conditions take the term "geographically challenged" to new heights.
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The United Kingdom, for the record, is the island of Great Britain with its islands, and Northern Ireland. If Barclaycard had wished to exclude Northern Ireland they could have used the term "Great Britain". "ROI" (Republic of Ireland) has been an independent nation for getting on for a century, and The Channel Islands are not now, and never have been, part of the United Kingdom.
One wonders, though, what the inhabitants of the Isle of Wight have done to upset Barclaycard!