Thanks GwynM. Yes it is the International Gates to which I refer. It is some time since I used Domestic/ROI.
Indeed, the security queue combined with the sometimes very long BMI check-in queue means that arriving for check-in one hour before a flight can mean no spare time, even if you wanted it, for refreshment, shopping etc.
To be fair to BMI they do police the queues very well and will call people forward if it is getting close to cut-off. I guess the numbers is due to the popularity of BMI and the fact that check-in at T1 is for all European Flights, Domestic and International.