Oakey got into the corridor where there were tons of cats hopping, running, rolling, swaying, crawling and possibly even flying around. How was he ever going to get a cat.
He even told Shaw that he would bring back more than one cat. He would need something that would attract a cat, but what a, mouse.

Wait Oakey did have a mouse, fake one that Valentine, his Owl had left behind at the Owlry a few days ago and replaced it with a real one.

he rummaged through his bag and found a slightly damaged rubber mouse that still squeeked when squeezed. He bent down on his knees and squeeked the toy a few times.