A company secretary is the officer of a company responsible for administrative matters such as maintaining registers of holders of registered securities, carrying out corporate actions and filing documents with the registrar of companies. A company secretary should also try to ensure that high standards of corporate governance are followed.
A company secretary may be an individual or a corporate body (i.e. a company). There may be a single company secretary or several joint secretaries. The company secretary of a public company (one that may sell its shares to the public) in the UK must be appropriately qualified. This means that they should be an accountant, a lawyer, a member of the Institute of Chartered Secretaries and Administrators (ICSA) or have other appropriate experience or qualifications.
The ICSA website provides a lot of information about the duties of a company secretary.
It is not uncommon for a company secretary to be a director of the company. Given that nature of the job it is not surprising that it is common for it to be combined with other duties in the areas of law, finance and administration.
It is fairly common for companies to outsource either the entire role (small companies often appoint an external secretary) or significant parts of it (for example, by using an external registrar).