Philip Reeve 
Kevin vs the Unicorn: A Roly-Poly Flying Pony Adventure [PDF ebook] 

Max and his best friend Kevin, the only roly-poly flying pony in Bumbleford, decide to enter the Magical Pony Club Steeplechase. Kevin is not particularly keen, as the other participants are all unicorns, and everybody knows that unicorns are quite snobby. But biscuits are promised, and Kevin wants to make Max proud. As the competition heats up, our inseparable duo uncovers a conspiracy to steal the precious Periwinkle Cup. Max and Kevin will have to intervene to stop the thieves and retrieve the stolen trophy.