The Circus Is Coming by Noel Streatfeild

Threatened with life in separate orphanages when their aunt dies, two children run away to search for their uncle who works for a circus and find that they can become a part of the hard work and colorful performances of the tenting season. From Goodreads.

Peter and Santa are orphans and have been brought up by their aunt who didn't give them a very good schooling but taught them that they were better than everyone else. When they run away to avoid separate orphanages and come to the circus they find out how little they know. Peter has a very tough time of it and is very annoying till he find his love of horses.
It is a book of growing up, finding out what you want in life and the hard work to get there. This is a children's story and of course has a happy ending.

This book qualifies for:
I Love Library Books Reading Challenge 2014
You Read How Many Books? Reading Challenge 2014
Crazy Challenge Connection - Oktoberfest
Goodreads Reading Challenge 2014
The Challenge Factory - R5: Team Challenge SSS
Crazy Challenge Connection A-Z Locations - 2014
Novel Books & Reading Challenges Tower Teams III