Amicus was the Unite Kingdom's second-largest trade union, and the largest private sector union, formed by the merger of Manufacturing Science and Finance, the AEEU (Amalgamated Engineering and Electrical Union) agreed in 2001, and two smaller unions, UNIFI and the GPMU. Amicus also organises in both parts of Ireland and is affiliated to the UK Trades Union Congress, the Irish Congress of Trade Unions and the Scottish Trades Union Congress.