The work will be divided into two chapters. Chapter one examines the political views of Thatcher and Delors and introduces the likelihood of conflict between them. The seeds of Thatcher’s ambiguous relationship towards the European Community and the SEA were sown in the work of Hayek, who promoted free trade and Dicey, who valued national sovereignty. The appointment of Jacques Delors as President of the European Commission, and Lord Arthur Cockfield as British European Commissioner with the Internal Market portfolio in 1985 brought together the central characters in the completion of the internal market. The factors influencing Thatcher’s decision to sign the Single European Act are discussed, and how she attempted to reconcile, explain, and limit the loss of national sovereignty, which she opposed. Chapter two examines the aftermath and fall-out resulting from Thatcher’s acceptance of the Single European Act and her endeavours to control further loss of national sovereignty and continued European integration. Thatcher’s claims of being `mis-led’ into signing the SEA, and her attempts to challenge the Foreign Office policy on Europe, which contributed to her downfall as Conservative Party leader and Prime Minister, will all be considered. The move towards further monetary, economic and social European integration, promoted by Delors and resisted by Thatcher, and the resulting divisions this prompted will also be examined.