Penguin Classics blue paperback, fox bookmark

I lost my blue Penguin Classics paperback of The Great Gatsby yesterday around 3pm near the Westquay South entrance in Southampton. It's a pocket-size edition with a creased spine and a tiny yellow bookmark featuring a fox peeking out from page 57. There's a coffee stain along the top edge of the back cover too. It has sentimental value—it's a gift from my late aunt and I really need it back. If anyone finds it, I'd really appreciate getting it back.