A statement said that Pope Francis had agreed with the decision but did not say whether it was the pope's idea that O'Brien should leave for what the Vatican said would be "several months for the purpose of spiritual renewal, prayer and penance".
The statement did not say where the Cardinal was going.
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A mass inhalation of "hippy crack" was carried out in the shadow of Parliament on Saturday in protest at the Government's drug policy.
Declan Donnelly is reportedly tying the knot with his manager partner Ali Astall in Newcastle today.
Warming up in the south but with breezy showers across Scotland today.