THE successor to shamed Cardinal Keith O'Brien will be unveiled today, with one of three clerics certain to become Archbishop of St Andrews and Edinburgh.

Archbishop of Glasgow Philip Tartaglia, who has been caretaker of the diocese since Cardinal O'Brien's enforced resignation in March, will introduce the new archbishop-elect at the historic Gillis Centre in Edinburgh.

There is speculation it could be one of a number of Vatican-based Scots.

Monsignor Leo Cushley, a priest from the Motherwell ­diocese who is working in the Vatican with its ­secretariat of state (the Vatican's foreign office) has been touted as being on a shortlist submitted to Pope Francis for approval.

Monsignor Patrick Burke, who works at the Congregation for the Doctrine of the Faith, could return to Scotland. He was recently in Scotland with Archbishop Gerhard Müller, the Prefect of the Congregation for the Doctrine of the Faith.

An outside bet is Bishop Hugh Gilbert of Aberdeen, who is seen as untainted by scandal and who, after his appointment in 2011, dealt promptly with a priest involved in the Cardinal O'Brien scandal.

The new archbishop's introduction will coincide with an announcement by the Vatican. The official installation will take place in several weeks.

Catholic sources remain tight-lipped on who will be appointed to take the helm of a battered and bruised archdiocese, still hurting from one of the biggest scandals to hit the Catholic Church in Scotland.

The Pope's ambassador to Britain, Archbishop Antonio Mennini, announced in May that a new Archbishop of St Andrews and Edinburgh would be appointed by the end of June, followed by the filling of vacancies at several other Scottish dioceses.

Although the Papal Nuncio's London office said Archbishop Mennini – whose role includes the recommendation of bishops to the Pope – had been "perhaps a little optimistic" and that there had been a delay in the appointment, the announcement has taken observers of the Church by surprise.

Cardinal O'Brien resigned from the post after admitting decades of sexual behaviour with other clerics and was exiled by the Vatican from Scotland in May. He remains a cardinal.