Toytown is of course Zara's favourite (and most famous) horse and I am familiar with Make Mine Music and Glenbuck, as well as some other horses, like Ardfield Magic Star and Tallyho Sambucca.
This is the first time I've read about Secret Legacy, however. Is it a relatively new horse or I had just missed it in earlier reports?
I remember not recognizing one of the horses she rode during this year's Gatcombe Horse Trials, although at the time I thought it was Ardfield Magic Star. It might have been Secret Legacy though.