It certainly looks like a hypericum and is very pretty - sorry I can't help :-( I have commented so that I can keep up to date with this.

What colour were the flowers, Steragram? Be interesting to see what colour those berries finish up - they nearly all start off yellow if it is a hypericum, and it does look like one. Maybe you've got a valuable 'sport' there...

These appear to be the flowers Bamboo.I have seen no trace of yellow ones. I have just been down to investigate again and pulled open a bud that was just preparing to open - they come out like this. Apart from that it looks like androsaemum.

Well its interesting, isn't it - those varieties of Hypericum that look like this usually have a red bit in the middle with the yellow round the outside, never seen one this way round.

OK so it must be Hypericum inversus... growing vigorously, hope it doesn't get too big - there isn't room there for another Hidcote...

It's a wait and see, but it looks so much like one of the H. androsaemum type, it'll hopefully not be bigger than those.

I don't know what those are so asked Mr Google, which said tutsan, which is what I thought to start with except for the flower colour. I have seen tutsan locally so perhaps that's where its come from, but it looks a lot better than the ones in the hedgerows!

Its really looking rather attractive at present so I'd like to keep it if practicable. Its got to just short of two and a half feet at the moment.

Yea, tutsan is a common name in the States for H. androsaemum and sometimes H. inodorum types.

Thanks everyone - if you lot haven't seen it before it must be a one off!

Well well - the little yellow ball in the centre turns out to be a bud. Ordinary yellow flowers are appearing now! Bit of a let down after all that, eh? This must be my week for feeling silly.

Don't feel silly! My hypericum never looks like that.

Well I figured they would, but this one's still unusual because of the red calyx (I think that's the right word..) and it confirms your original guess of hypericum, Steragram.
Plus, at our ages, quite frankly, we're well past feeling silly, whatever we do, to hell with that, nowt wrong with a bit of silliness;-)

I've had so much practice through life that I can still do it very easily!

The red calyx is very pretty - in fact the buds are really nicer than the flowers...

Well Melchi, there are so many different sorts aren't there...