Hi. His stuff in in Australia with you, where is he now? Does he have friend or relative living near you?
Well, managing "stuff" can be complicated, there is surely a lot of stuff in Ireland also. You can ask him for money for a locker rent and a moving company and send all that there or ask him for firend or relative to pick it up, or else it will be for free on the border of the road. The important thing is to give him a date where you will get rid of it or else he will always use you as a free stockroom. If he don't react it will be his fault. Make sure to always communicate with a registred letter in regard to those thing to not have legal problem in the future.