Complex sentence: There were differences within the Cabinet over Thatcher's perceived intransigence in her approach to the European Economic Community--in particular many leading Conservatives wanted Britain to join the Exchange Rate Mechanism, a move which Thatcher did not favour.
Split into simpler sentences: There were differences within the Cabinet over Thatcher's perceived intransigence in her approach to the European Economic Community. In particular, many leading Conservatives wanted Britain to join the Exchange Rate Mechanism, a move which Thatcher did not favour.