What to do if I find a passport I'd reported lost/stolen?

Never travel on a passport if it has been reported lost or stolen. You run the risk of being stopped at border crossings, as Interpol keeps a record of all reports of lost or stolen passports.

You should return the passport to the Embassy of Ireland for cancellation.

The Embassy is located at:
Whitehall Mansions
Ix-Xatt ta’ Ta’ Xbiex
Ta’ Xbiex
XBX 1026