The minister was preoccupied with thoughts of how he was going to ask the congregation to come up with more money than they were expecting for repairs to the church building.  Therefore, he was annoyed to find out that the regular organist was sick and a substitute had been brought in at the last minute.  The subtitute wanted to know what to play.
"Here's a copy of the service," he said impatiently.  "But you'll have to think of something to play after I make the announcement about the finances."  During the service, the minister paused and said, "Brothers and Sisters, we are in great difficulty; the roof repairs cost twice as much as we expected, and we need £4,000 more.  Any of you who can pledge £100 or more, please stand up."
At that moment, the substitute organist played the National Anthem... and that is how the substitute organist became the permanent organist!