This makes lots of sense. Also, I think I suggested this further up one of the threads, but I wondered if it is in part because Mrs Marlow still worries about Ginty after the Traitor stuff and being trapped after a bomb, and thinks it will help her.

Just had an additional thought, could it also be that she can't resist buying Catkin as well as Chocbar, and Ginty's the only child he will suit? She's very encouraging when Lawrie and Peter first discuss having the Idiot Boy, so perhaps she's just desperate for horses after all those years of Hampstead.