Charged with drink driving although I was not the actual driver

My partner has just been found guilty of drink driving when on the night in question he wasn't driving the car. He had let his friend use the car, who unknowing to my partner was not legal to do so. Apparently a police officer persued my partner's friend, who abandoned the car outside my partner's residence and threw the keys at my partner before running off. The friend did attend court to give a statement to the effects, alongside two people who were in the residence having a drink with my partner on the night in question. The reason he was found guilty was he had the keys to the car when the police officer pulled up. A statement was not given by the officer until the morning of the court date some eight weeks later; also video evidence of my partner on that night telling the police he was not driving was ignored and he wasn't interviewed. Please could you offer some advice.