After the fall of the junta, Maria Becket refused the position of Greek Ambassador to the U.S.A., but later returned to Greek politics through her work with Minister Constantine Mitsotakis and his party New Democracy on a number of political issues.

Maria Becket worked with Mitstotakis when he was Minister of Co-ordination and Minister of Foreign Affairs, and appears to have been a key point of communication between different bodies and individuals and on various projects, including the establishment of a National Technology Centre for Greece, the development of technical universities, Greek railways, the reduction of pollution in Athens, the preservation of the Acropolis, the establishment of Greek cultural centres in the USA and other matters of foreign policy.

Maria Becket was involved in New Democracy election campaigns, particularly in the 1985 campaign which utilised the American Sawyer Miller Group. She was also involved in the development of the apolitical 'Citizens' Movement' in Greece. She returned to work with Mitsotakis in the mid-1990s as part of Monitor Group's development of an economic strategy for a 'competitive Greece'.

In the 1990s, Becket continued to be involved in Greek international relations including Greece's relationship with the UK. She formed a friendship with Sir David Hunt, the British diplomat, and his Greek wife, Lady Iro Hunt, and worked with them on Hellenic events in Britain including the 2500th anniversary of democracy in 1992. She also hosted Members of the House of Commons and House of Lords on a parliamentary visit to Greece in 1993. Maria Becket continued to take an interest in Greek politics until her death in 2012.