Not that simple at all. How did the black guy get a receipt for it? Once a car is stolen the number plate if flagged. If anyone had tried to sell the car under the original numberplate the DVLA would have informed the police It does occasionally happen that the police neglect to inform DVLA that the car has been stolen, and then the thief sells the car on, but with either no V5 or a forged one. Because the car was reported stolen, it would remain on the police database, but as far as the DVLA are aware, it is a legal sale, even though it is not such. Without knowing more details, it is impossible to say what happened in your case, but there really is no legal way of selling a car you do not own.