Canon James Cronin, dean of Southwark's Roman Catholic Cathedral, has been appointed as national director of Missio, the church's support organisation for overseas mission. Fr John O'Toole has been named as his successor at St George's.
Canon James Cronin was appointed as administrator of St George's Cathedral in 1996. His job title was later changed to dean.
Canon Cronin's time in Southwark has included the visit of the Dalai Lama to the cathedral in 1999 and the recent redevelopment of the Amigo Hall.
He has has also served as an elected governor of Guy's and St Thomas' NHS Foundation Trust.
Three years ago the dean was presented with a special award by the Southwark Civic Association.
On Sunday morning the congregation of St George's was told that Fr John O'Toole will be the new cathedral dean and will take up his new role in June.
Fr O'Toole is currently director of the Christian Education Centre for the Archdiocese of Southwark. He was born in Dublin in 1950 and brought up in Kent.
After ordination in 1978 he served as an assistant priest in Lewisham and Merton before he was appointed parish priest of St Paul's Thamesmead.
From 1999 to 2004 he was parish priest of St Andrew's Thornton Heath where soon after his arrival the parish hit the headlines when a man went on the rampage with a samurai sword during a Sunday morning Mass.
Fr O'Toole is a member of the English Anglican-Roman Catholic Committee.