Not always the case though and a string of winners can happen in the randomness of betting, especially at shorter odds. Their first step is usually to ban you from their offers before closing you down. Welcome to play their slots and casinos though!!
Long term this is not sustainable unless you have an endless supply of people willing to open accounts for you. The books close anyone who they feel might make a profit or have an edge.
The books should be made to lay any bet to lose £1000 to anyone, which may make them sharpen up their...