In 2012, the European Union received the Nobel Peace PrizeĀ for its contribution to the advancement of peace and reconciliation, democracy and human rights in Europe. Having worked at the European Commission over a period of 36 years, Catherine Day played no small part in these advancements. She influenced and shaped the EU landscape by championing enlargement and helped build, plan and drive the development of the EU.

As secretary-general of the European Commission since 2005, Catherine Day is the most senior civil servant in the EU and one of the most influential civil servants globally. In her role as secretary-general, she helps the president of the Commission to set priorities and then works with the machinery of the Commission to deliver on those priorities in all of our interests.

Brought up mainly in Dublin, Catherine Day studied history and politics at University College Dublin and graduated in 1974 with a first-class honours BA degree. She achieved her MA in International Trade - again from UCD and again with first-class honours - one year later. She got her first job - with the Investment Bank of Ireland - while still studying for her master's degree and began her European apprenticeship shortly thereafter when she was recruited as EC information officer with the Confederation of Irish Industry.

In 1979, Catherine's career took her to Brussels, where she was appointed to an administrative position at the European Commission in the Directorate-General for Internal Market and Industrial Affairs. She has described the decision to move to Europe as an easy one simply because Brussels was home to the major institutions and was the heart of the European project, a subject about which she has always been passionate. Back in the early 1980s, the atmosphere in Brussels was, at times, bleak, and the European Community was often criticised. Even then, however, Catherine Day was steadfast in her belief in the endless possibilities of the Union to reshape itself into a powerful engine for growth and the global good.

From 1982 to 1984, Catherine Day served in Commissioner Richard Burke's cabinet in the area of personnel and administration. In 1985, she joined Commissioner Peter Sutherland's cabinet to work in the area of competition, where she was assigned to two politically fraught and sensitive areas: state aid and infringements. The dismantling of state aid met with fearsome resistance, and Catherine Day played a central part in the negotiations that resulted in the opening up of markets. Her abilities and successes were further recognised by UK Commissioner Sir Leon Brittan, who appointed her to his external relations cabinet in 1989. There she worked on relations with Central and Eastern European countries at that critical time in the immediate aftermath of the collapse of communism and the fall of the Berlin Wall when these countries entered the pre-accession process to fulfil their desire to become full members of the EU.

Rising steadily through the ranks in external relations, Catherine became deputy chef de cabinet to Sir Leon in 1995 and director in 1996. A year later she moved to the Directorate-General for Enlargement, where, as director, she was now fully responsible for relations with the then-candidate countries of Central and Eastern Europe. In 2000, she attained the rank of deputy director-general in external relations, a role that included responsibility for the Western Balkans and the Mediterranean. By this stage, Catherine Day was working on some of the EU's most pressing issues. In 2002, she was promoted to director-general and moved to environment, where she strove to enforce environmental laws, set new standards and tackle global warming.

While working in external relations and enlargement, Catherine Day was deeply involved in the growth of the Union from 15 to 27 countries. Her role involved working with applicant countries to help them understand and prepare for membership. She was struck by the willingness of accession countries to completely transform their societies, economies and institutions to join the EU, and this made her appreciate anew the benefits of membership. Although enlargement was not universally popular initially, Catherine viewed it from the outset as a huge political and economic success. In her own words, the post-enlargement phase was merely a bit of indigestion.

When Catherine Day became the most senior civil servant in the European Union in 2005, her experience of the enlargement process served her well. As secretary-general, she is the link between the technical enabling work of the directorates-general and the political work of the College of Commissioners. Among her many achievements since 2005 is the setting up of a landmark cross-commission programme of digital transformation to help rationalise, redefine and redesign how we communicate online.

Catherine Day is being honoured today for her exceptional achievement. As the first third-level college in Ireland and one of the first in Europe to recognise European studies as a distinct discipline, the University of Limerick has a long-established reputation in this particular field of knowledge. We are, therefore, especially proud to honour this outstanding Irish woman for the key role she has played in building the European Union to enrich all our lives on so many levels - from the creation of a marketplace of 500 million people to gender equality and the institutionalisation of women's rights, free public healthcare, air travel liberalisation, consumer protection and much more.

Catherine Day received an honorary doctorate from UCD in 2003. Today it is our turn to pay her tribute.