having also once been new to all this, I too made vast leaps of attribution based on single examples, in the early days, and come unstuck - it's easily done.
Kny's work is more complex, usually, than the design on your vase................. in the early days with Stuart his trademark, frequently, was the v-grooved outline on oval eye-shaped leaves which appear on many of his floral designs, and there's a deco look often to his patterns.
With Stuart, identification isn't helped due to the truly vast quantity of different designs they produced, and when so many designs were kept in production for a very long time - personally I'm happy to say this is probably John Luxton, and almost certainly not Kny. If the auction house attributed this particular pattern to Kny, and now are unable to offer provenance, I'd be less than happy with their confidence.
On the Board's archive we have a lot of Stuart cut designs - have a look some time.