How did the angel come to be on top of the tree?

When four of Santa's elves got sick, and the trainee elves did not produce the toys as fast as the regular ones, Santa was beginning to feel the pressure of being behind schedule.

Then Mrs. Claus told Santa that her Mom was coming to visit.
This stressed Santa even more.

When he went to harness the reindeer, he found that three of them were about to give birth and two had jumped the fence and were out Heaven knows where.
More stress.

Then when he began to load the sleigh one of the boards cracked, and the toy bag fell to the ground and scattered the toys.

So, frustrated, Santa went into the house for a cup of apple cider and a shot of rum. When he went to the cupboard, he discovered that the elves had hidden the liquor, and there was nothing to drink. In his frustration, he accidentally dropped the cider pot, and it broke into hundreds of little pieces all over the kitchen floor. He went to get the broom and found that mice had eaten the straw end of the broom.

Just then the doorbell rang, and irritable Santa trudged to the door. He opened the door, and there was a little angel with a great big Christmas tree.

The angel said, very cheerfully, "Merry Christmas, Santa. Isn't it a lovely day?
I have a beautiful tree for you.
Where would you like me to stick it?"

And so began the tradition of the little Angel on top of the Christmas tree...