The Hypericum you have there is most likely Hypericum Androsaemum, and they are indeed attractive and have a long season of interest with berries forming after the flowers, and they turn from red to black, often used for flower arranging. They also don't grow too tall. Usually around 50cms and seldom more than a metre in height.
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The second looks like one of the knapweeds ... Centaurea nigra
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
The Knapweed I’ve kept for a few years though I’m not sure why other than it’s a self contained clump it seems.
Ive let it run wild in the corner this year and the Hypericum flowers look rather attractive to me.
I believe that I also found one in Bromley Gardens today, as it happens - much much larger, so I may need to move it to keep it.