 Due to the linguistic, cultural and legal (both as common law countries) similarities between the UK and Ireland, many businesses in both countries have operations in each other country.Both countries have each other as their biggest business partner, and both in the same trade organisations include the European Union and World Trade Organization.Examples of notable British companies that have an Irish operations come as diverse as the supermarket chain Tesco (Tesco Ireland), the department store Marks & Spencer, the commercial bank RBS which trades as Ulster Bank, telecoms company BT (BT Ireland) and electric company SSE plc (Airtricity).