xtype, rtf press release on their website . . .
"The Aer Arann Isle of Man route will also bring another first to London City Airport as its debuts the 72-seat ATR72-500. It will be the first of its type to operate into London City, bringing high standards of passenger service to the route. Aer Arann is currently participating in a certification programme with the manufacturer, ATR, the UK Civil Aviation Authority and London City Airport."
I would suspect Glasgow was a victim of reducing their presence in Cork rather than poor performance as its operation was linked to the Dublin route, last in/first out if you like.