If he has his PRSI record from Buncrana (Dept of Soc Protection records office) that should show his full record. That’s all he needs. Just attach a copy with perhaps list of most recent employers. If he wants UK or other relevant foreign service added to his Irish record, that’s a bit more complicated as Buncrana need to do the checking with the overseas Depts (eg Dept of Work and Pensions in UK). That may take a little time to confirm the details (after you give Buncrana the overseas work history).