Any vexillologists out there?

During the marvellous week of our pilgrimage to Lourdes - what a boost it gave to our optimism and self-confidence - there was an interesting phenomenon which I haven't seen commented on elsewhere. In front of the basilicas, there are some flagposts. While we were there, two flags flew: the Cross gules on the argent field, for S George and for England; and the arms of the See of Canterbury: azure an archiepiscopal cross in pale or surmounted by a pallium proper charged with four crosses paty fitchy sable. What a pleasure it is always to see these arms, reminding us of happy days when the Archbishop of Canterbury received the pallium from the Successor of Peter (of whom he was also, I believe, Legatus natus) as a sign that he was a major Archbishop in peace and in communion with the Holy See. What a pleasure just for a moment to be able to forget all that has divided us since 1559; to imagine that one has just woken up from a gross nightmare and that the Cardinal Archbishop of Canterbury is leading a great Catholic pilgrimage - greater even than September's - from an England which had never been sundered from the rest of Christendom.

Now to come down to earth: what is the convention at Lourdes with regard to those flagposts? Which countries and which prelates normally get to have their flags flown? Despite the crowds of Croats, Italians, and Irish, I didn't see their flags.