I've just had one of those conversations where neither contributor could remember anything in detail but between the vague recollections and incomplete sentences we managed to cover the topic (English playwrights and actors of the 20th century) adequately.

This made me think about producing a dichotomous key for use on such occasions. Something along the lines of:

1. That man, you know the one, he:

• wrote that play (go to 2)
• was in that play (go to 3)

2. You know, the play set in:

• northern England (got to 4)
• London or the south (go to 5)

3. You remember the actor. Yes, you do.

• He's dead (go to 6)
• He's still alive (got to 7)

You get the idea ...