Was he working for the company on 5th April or was he made redundant before that? On what date was the company liquidated do you know?
If he was made redundant prior to the 5th April then he should have been issued a P45 (possibly by the administrators). I would suggest he contact the administrators, if they don't hold the records then his local tax office should be able to give him an official statement of tax paid for that year which although isn't a copy P60 is a valid alternative.
