I suspect this neighbourhood is one where on street parking seems to be at a bit of a premium. Plus the local authority charge a ridiculous cost for a parking permit and they are as rare as rocking horse poo.
Also, just around the corner is one of those 'wardens from hell' parking attendants with the peak of his cap pulled down and armed to the teeth with a fresh pad of parking tickets.
Thus, our hero used his initiative and used the roof of his house to park on - first class.