A few years ago I was taught a simple mnemonic to help assess how to deal with an interruption. For the sake of this it is assumed that I am in the middle of something important and am trying to decide if the interruption is more important than what I am doing:
Greet - say hello politely and do not continue the chat. Works for when passing people in the corridor or street.
Receive - take the letter or parcel they have given you, do not open it in their presence, and tell them when you will deal with it if they need to know.
Accompany - take them to the colleague they need to see if it isn't you. Or the underling who can handle it for you. Or the boss if it is above your pay grade.
Confer - set aside five minutes to assess if this is something important or not. Then do one of the other things.
Engage - drop everything. This interruption is your new priority. Take five minutes to renegotiate the deadline of the other thing, call and reschedule or diary time to complete.
See off - chase them out of town, call the police. Shout for help, hand over your wallet. Not necessarily all of these and maybe not in that order.
(This post builds upon #ministry tip 129)
(Thanks to Bryn Hughes of Marc Europe at the training course 'Management Skills for Christian Leaders' 1990)