I think I may have found The Toy for Girlcat. I had some Zooplus points so when I ordered their food I got a pack of 6 Trixie toy mice. Just 5cm long plush, with a stringy tail & with catnip inside.
She's completely forgotten i't suppertime any minute, and is flinging the one I offered her around the room with gay abandon. Been at it longer already than any of her other toys can hold her interest for (e.g. Da Bird).