Premier Medical & Industrial Equipment (Pty) Ltd v Winkler [1971] 4 All SA 94 (W) per Hiemstra J.

“To go marauding among his master’s suppliers and customers in order to build up his own business is certainly one of the grossest breaches of fidelity that can come to mind.  A good example of that is Wessex Dairies Ltd  v  Smith, (1935) 2 K.B.  80.  In that case an employee who, while still in the service of his master, solicited the customers of his master to transfer their custom to himself, was held liable in damages even though the transfer was to take effect only after the service had terminated.  It was held that he committed a breach of his duties to his employer.

There are several other cases supporting this proposition but none of them go so far as to lay down that the duty of fidelity persists after the termination of the contract of employment.  Such a duty could be introduced in the relationship of master and servant by means of a specific covenant to that effect.