Angela and Ian come to stay with their uncle and help look after the two small ponies, Magic and Moonshine, Uncle Arthur's 'pantomime stars'. At last the two children, who have never had a permanent home, feel that they can settle in a proper home - until an accident with Magic makes them wonder if they'll be allowed to stay.
Gillian Baxter was a British writer of children's books. Her books were mainly pony books about horses, although one book, The Knightsgate Players, was about acting. Baxter also wrote under her married name " Gillian Hirst".
Remember reading this when I was a kid. Orphaned siblings go to stay with their eccentric uncle in London while an aunt goes off to look after another relative. To their delight, they learn that their uncle has 2 Shetland ponies (Magic and Moonlight) that live in his back yard and work at the pantomime! Such a sweet little pony book, trying to track the others down at the moment.