If he has social welfare free travel pass with photo, that may suffice.
Unfortunately it seems to depend upon where you go.
A few years back when I opened a new bank account the official (a senior one) declined my bus pass. I politely told her to ring head office. She was very apologetic when she returned.
I was told I needed one by my local Branch of Ulster Bank by the lady at the customer service desk, because I needed two forms of id, because I am a foreigner.