Deacon's professional career started in 1992 at
University of Wales Institute, Cardiff (UWIC) when he was employed to teach public affairs to the National Council for Journalists professional training courses. He served in the Business School for the next 8 years finishing as the director of research on the MBA programme. In 2001 he helped start the Humanities courses at UWIC in the School of Lifelong Learning. The first cohort had around 45 students, the degree programmes now, in the School of Education, have around 350 students connected with the Humanities pathways. In 2006 he became Head of the newly formed Department of Humanities. Then in 2008 he became the Acting Director of Research for the School of Education. In April 2010 he was awarded a personal chair by UWIC and made his inaugural lecture on
Politics and Humour in February 2011. Deacon left UWIC in July 2011 and from the Autumn of 2011 he worked with the Department of History at the University of Wales Trinity St Davids. Recently Deacon is now working at University of South Wales teaching History in 2026 Deacon was previously associated with the running of the
ERASMUS programme in UWIC. In this respect he has presented on the subject at academic conferences and published in an academic journal. Deacon has also had a long period directly involved in politics specifically for the
Welsh Liberal Democrats. In 1992 and 1997 he was the agent in the Rhondda Valley, the later time for Dr
Rodney Berman the ex-leader of Cardiff City Council. Although he stood for council office 15 times he was only successful twice, he served on Van Community Council as the only elected Liberal Democrat in the
Caerphilly County Borough area. In the 1997 referendum Deacon served on the Board of the Yes for Wales Campaign, directed by
Leighton Andrews. On the night of the referendum itself he provided the expert media coverage for
ITN. In 1998 he worked for a while in Westminster in support of the Welsh Liberal Democrats during the drafting of the
Government of Wales Act 1998 under the late Lord
Richard Livsey. In 1999 he was seconded to the National Assembly for Wales for one year to help set up the administrative structures. There he worked directly to
Lord German, the then leader of the Welsh Liberal Democrats. Deacon has made numerous media appearances for BBC programmes such as AM/PM, the Politics Show, television series such as
Coming Home and The History of Wales, as well as radio programmes on Radios 2, 4 and Radio Wales. Deacon became the Chair of the Campaign for a Welsh Parliament between 2005–2008. He also serves on the Boards of the
National Library of Wales Political Archives, the Welsh Council of the European Movement, History Research Wales and the Liberal History Society. In addition Deacon is the convenor of the
British Liberal Political Studies Group, part of the
Political Studies Association. Deacon was an advisor to the
Electoral Reform Society on the referendum in May 2011 on the Alternative Vote. He has appeared as an expert witness before many Westminster and Welsh Assembly Commissions on electoral and political reform. In recent years Deacon has also advised the
WJEC and Qualifications Wales on the syllabus for the Welsh AS and A level programmes in Politics Deacon has also been a key note speaker at the
Lloyd George Society, the WJEC politic students' conference and at a number of European Universities including the
Ghent University, Johan Gutenberg University in Mainz and the University of Plovdiv in Bulgaria. In 2010 Deacon was made a royal fellow when he was elected to the Royal Historical Society. ==Publications==