For example, if it has been the habit to release staff when the day's work is done (such as, today's newspaper is printed), then that becomes the de facto contract of employment.
Over many years of incremental negotiation, the original rationale may be lost and a point reached where all workers are being paid a supplement merely to complete a normal shift.
Crozier described as "cobblers" claims by the Communication Workers Union deputy general secretary Dave Ward that the way Royal Mail made its employees work amounted to "slavery".
One example of such practices was paid overtime within normal working hours, after workers completed their scheduled delivery rounds early.
In 1584 another secretary of Queen Elizabeth I, Francis Walsingham, referred to Spanish practices in a way that meant they were "deceitful, perfidious and treacherous".