Jeremy Strong 
Pirate School: The Birthday Bash [EPUB ebook] 

Patagonia Clatterbottom, the headteacher of Pirate School, is having a birthday. She takes the children to shop for a party and they are ambushed by the children of the School for Young Highwaypersons who take all the food. But Master Skittershins, the dancing master, secretly trains them in high kicks, etc and they go back to fight-dance the highwaypersons. They get the party food back and all ends happily when the highwaypersons turn up at the ship — but this time to join in the party.