Manager in public limited company

No. One person cannot do both. 

In many organization, the directors themselves plays the role of a manager, but it does not mean that the role of the two important ranks of the company is same. A director can be an employee, member or any other person, who is unanimously chosen by the company’s shareholder at the general meeting. In contrast, a manager is a paid employee of the company who possesses a substantial amount of knowledge, expertise, and abilities to manage the organization.