有冇知道咩係agency by estoppel

Sorry I am a poor Chinese typist, may I use English.

It is a principle in the agency law. Estoppel means somewhat like stopping and denying someone saying something even it is the truth.

If a person did something or said something that makes other people thinks he is an agent 代理 of another person, (he is in fact not an agent!), he cannot say (estopped from saying) at a later stage that he is not an agent.

He will in law be treated as an agent, though he is not a real one.