I have a lamp-base in an identical pattern (to the one one the site) with a 'Made in Sweden' label and have always considered it to be Elme.
The finish and colouring of it is spot-on for your vase, Pip, so I'm convinced you're correct.
I think I know which buyer you mean - he's outbid me, and bought from me in the past. I didn't realise he was a collector, though - with the amount he bought, I always assumed high-end dealer.