When is the clause in «الذي كان معنا أمس رجل عالم» especially effective?

Defining the Subject by a Relative Pronoun: Purposes and Rhetorical Applications

• When the hearer does not know the name but recalls yesterday’s meeting
• When the hearer knows nothing of yesterday’s meeting
• When the speaker is issuing an order rather than information
• When the relative clause is entirely omitted