Control of company affairs: a reduced number of directors alone does not establish public non interest under the relevant test. Administrative guidance directs that a public company with fewer than six directors is not to be deemed one in which the public are not substantially interested solely by reason of that fact. The applicable explanatory test focuses on control of the affairs of a company, a qualitative inquiry distinct from day to day management, and tax officers must assess how control is exercised rather than rely on the board's numeric strength.