Or got one from a different country?
possibly.
I can't imagine a country keeping an invalid passport lo these many years. Passports, expired or otherwise, are usually voided, and returned to the owner. He could leave England without a passport, but he would have to have a valid passport from somewhere to enter yet another country; any country.
Unless, for some reason, British authorities pulled the Indonesian passport, but he had possession of another passport from another country, and left England illegally. Then, they might be keeping it, and the case is still open. If he returns to England, would he then be subject to arrest?