based on section 190 contracts act 1950..
If a principal make third party believes that A is his agent (even if they're not), and A acts on this belief, the principal can't deny that A is his agent later and is bound by A's actions
Freeman & Lockeyer v Buckhurst Park Properties Ltd :
A company let K act as managing director without officially appointing him. K hired workers for the company. When the company refused to pay, claiming K wasn't authorized, the court held that by allowing K to appear as managing director, the company had to honor K's actions.