By a salt lake just a hundred yards inland from the beach/dunes
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The photo, enlarged, shows the swollen glossy red capsules which are longer than their perianth segments. And the long sharp-pointed leaves. Habitat right - dune slacks and sandy salt-marshes.
Yes, this is amazingly worldwide (except Orkney!) well, except quite a few places.
This is a bit revealing -
http://www.brc.ac.uk/plantatlas/index.php?q=node/425 - I had always thought it was across the UK as I had seen it in a few (unrecorded) places in North Wales.
Graeme/Jo, do have experience of it in the UK?
There are so few UK posts.
But hey, see this one.
It is mentioned in an OU video (from 1980's?) as present at Braunton Burrows, North Devon. I did not record it at Swanage Sand dunes, Dorset, though I have made several trips there, but I wasn't looking specifically for it.
It is not at all rare on the Welsh coast.
Lat/Lng: 43.4066, 6.7313