Thank for that Gerry.
Unfortunately, there are a lot of changes coming in 2020 with the new National Pensions Framework, which I understand is at the moment a proposal and hasn't been approved / legislated for.
As he has only been in Ireland since 1998, under the current rules at age 58 with 16 years of full contributions, if he continues to pay voluntary contributions up until age 67 (changing from 66 in 2021), he would be entitled to the full state pension with 24 full years of contributions.
Unfortunately, these rules are going to change in 2020 and no-one seems to know for sure what they are going to change to.
I spoke to someone at the Citizen's Advice Bureau who also said that the 'Homemaker' allowance looks like it's also going to be changed to the detriment of women who stayed at home to look after children - in saying that, the 20 years granted under this scheme was perhaps very generous.