He is well known for being commissioned to paint the Northern Ireland Assembly in Session, becoming the second artist to do so in the history of the State. Another major piece he was responsible for was a portrait of Michael Collins which was unveiled in the Glasnevin Cemetery Museum gallery for the annual Collins-Griffith commemoration in 2015.
Murphy was presented with the Bass Ireland Prize (1994) and the Ireland Fund of Great Britain Annual Arts Award (1997). He has held several solo exhibitions with the Gorry Gallery, Dublin, and the Emer Gallery, Befast, and is represented in the collections of the Ulster Museum and the Arts Council of Northern Ireland, among others.
Noels work has been collected worldwide with the latest , painting of Michael Collins , going to London.