Polish man living and working in UK since 1992 ...

Hello again.
I have a cl who came to UK from Poland in 1992 as a student and during this period he worked part-time until he returned to Poland in 1997.
He returned to UK in 1998 and worked part / full time until 2001 when he returned to Poland again.
Returned to UK 2001 and again worked part / full time until 2004 when he returned to Poland.
Returned to UK 2004 and worked part / full time until 09/09/08 when he had to give up work because of illness.
He has received a State Retirement Pension Forecast for when he retires in 04/13 and he will receive £58.75 pw.
He has also just received £250.00 Winter Fuel Payment.
He has been refused PC because he does not have the right to reside because he has never registered his work, and there is no record of authorised work at the Home Office prior to 30/04/04.
Cl admits he has never registered work.
He lives with his daughter who is also Polish and i am going to explore whether he has any rights to PC through her status as an EEA dependant family member.
I am looking at grounds to appeal PS decision on cl rights rather than through daughter and any ideas would be much appreciated.
Thank you.

Assuming he was on a student visa when he first came to the UK part time work was (probably) OK. Before 2004 he would have needed a work permit to work in the UK legally - did he ever have one?

Thank you ariadne2 and from gathering further information cl is living with his daughter who is also Polish and employed 20 hours per week. would this mean cl has a right to receive Pension Credit because he is dependant on a family member who is an EEA national who is economically active ?
Cl has never obtained a work permit and neither has he ever registered his work.
Any further thoughts on this and thank you again.