Lustre bud vase?

I have researched as much as I can and other websites indicate this could be British, from Knottingley. I know it has been used as a bud vase but it seems almost like a bottle or jar? It has Reg. N. 905918 on the bottom but I could not find this number on the glass pattern register.The colour is amazing. When the light shines on it it is almost a mirror finish. I confess I just spotted it in the window when I walked past a charity shop and my Magpie traits kicked in.

If anybody has any idea I would be grateful.

Thanks

Elaine.