"Perhaps it doesn't operate earlier because the fleet is fully utilised on other routes earlier in the day?"
Yes that is true, the fleet could be fully utilised earlier in the day, I just thought it might be worth trying the flight with a new timing to maybe capture some connecting traffic before cancelling the flight altogether (if indeed that is what has happened and its not just a seasonal cut). Although from what I understand, it seems quite a popular route and whilst I know this doesn't mean its making a lot of money, it is still quite a new route, with Aer Lingus Regional/Aer Arann operating it anyway.