I would say call into the branch as they may have ran you through a points system such as time at current/previous address, whether you are a home owner or renter, whether you are in your current job a short period of time. They won't neccessesarily go beyond this as in look into your deposits with them. You could also check out your credit history with the Irish credit bureau. They had an error on my report a few years back and I had them correct it. Some institutions will not give you a loan if you have a history of paying back loans early but i'd say it was the points as mentioned above.
If you've never had a loan out- This could also go against you as you have no credit history!