I was wondering how the O'Leary use magic if Marleybone has no magic? Even the balance instructor in Ravenwood says," I came from a place called Marleybone that had no magic." So why do the O'Leary use magic?
Of course, the same applies to you - if Marleybone has no magic, then how can a wizard function in Marleybone?
The most likely answer is that - being part of the Spiral - Marleybone DOES have magic but what it doesn't have is anyone there that is trained in using magic. At least in Dog society. Which is why the Balance instructor left (to learn to use magic). Kind of how magic works in the everyday world in Harry Potter, but you go to one of the schools to learn how to use it.
If that' IS the case, then the O'Learys could have learned the same way (or been taught by someone in their gang who came from elsewhere).