I am not a lawyer and it's always best to seek their advice, that being said two questions come to mind, the crown would have given your lawyer a disclosure statement of the facts, in that disclosure did it state they had a witness you were driving? Did you tell the police you were driving? If it was an hour later and you were home I don't know how they could charge you with DUI as you could have started drinking at home, to me that is reasonable doubt.