[4] He began his ministry with a curacy at St Mark's North End, Portsmouth.

In 1987 he became Principal of St Stephen's House, Oxford,[5] an Anglican theological college.

In 1995, he was chosen to be the first Bishop of Richborough, a provincial episcopal visitor in the Province of Canterbury for traditionalists who reject the ordination of women as priests.

[7][8] In October 2010, Barnes was interviewed by The Tablet magazine on the possibility of joining the proposed personal ordinariate in the Roman Catholic Church for former Anglicans (which was established as the Personal Ordinariate of Our Lady of Walsingham in January 2011).

He was ordained to the priesthood on 5 March 2011 by the same bishop in the Cathedral of St John the Evangelist, Portsmouth, for the Personal Ordinariate of Our Lady of Walsingham.