Gray tabby cat with neon green collar

I lost my gray tabby cat yesterday around 3pm. He's medium-sized, about 10 pounds, with a white patch on his chest that looks heart-shaped and a tiny notch in his left ear. He’s wearing a neon green collar with a small silver bell. I last saw him near the Arndale Centre on Market Street, Manchester, heading toward Exchange Square. He’s shy with strangers but incredibly sweet, and my kids adore him—the cat means the world to us and I’m really worried he’s out there alone. If anyone’s seen him, please message me here; I’d be forever grateful and can arrange to meet wherever is convenient.