Whether someone has been convicted or not surely isn't the issue. I would imagine that paedophiles who have been convicted of anything are probably greatly outnumbered by others who have never been convicted.

Open plan libraries, rather than the more traditional model where there was a children's library, and a separate reading room and so forth, have always struck me as a rather silly development. Presumably introduced as a penny pinching way to cut down on the number of librarians employed.