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The plant was about a foot high, about the size of cow parsley. I'm not sure it was Hypericum, but it is hard to tell as it was so dry and brown.
A few things I've just read: The dead stems are best left in situ over winter to protect the crowns from frost. Sedum can be propagated by division in spring. Oh, and its also excellent for bees and hoverflies too.
Have just added two Sedum observations of mine to ispot - one summer, one February!
Lat/Lng: 51.464594, -0.032961
OS grid ref: TQ367757