Where to locate shares

My elderly relative held shares in an Irish company that is still actively trading today. However, there is no paperwork—such as share certificates—to confirm his ownership. It’s possible the shares were held electronically. He never sold them and had been invested since the early 1990s. Is there a specific body or registrar we can contact, where we can provide his personal details to verify whether he still holds these shares?

Registrar is of use, if the shares are in his name. However, this appears not to be the case from your post. Do you know what broker he used? They are probably in that broker's nominee account.

Quite a lot are handled by Computershare so they may be worth trying, although they are usually pretty painful to deal with

The company's website should have a shareholder's section that explains what to do and who to contact. Maybe if you could name the company then people could offer more specific advice.

I believe that companies have to list their shareholders when filing their B1 annual return. Copies of these can be purchased from the company registrations office for €2.50.