Right, as an ex FCO officer in the consular section, this is somewhat of a speciality of mine.
However, the others are right. If he is a British National then the Embassy can help him out. As long as checks with the UK passport office go OK, then an emergency passport will be issued. There is a fee, but that can be paid by yourself. HOWEVER, you must report it as a lost passport, not a stolen one. If you do, they may ask your dad to go throught the rigmarole of reporting it to the police and getting the police report form them. You can send money (i'm not sure of the fee) to the Desk Officer in the London consular section that deals with the Philippines, Once they have it they will instantly authorise the release of the passport. They will also accept some extra funds to pass on to him as long as they recieve them in the London office.
It really should be a straightforward procedure. Give the London desk a call. Call the switchboard and ask to be put through to the Consular Desk Officer for the Phillipines. They will tell you where to go from there.
Good luck. Sounds like he should deffo be back here with you.