It looks a bit like an hypericium don't know if that's how you spell it. I can't see the flower very well but looks like that to me.

Yes hypericum not sure which though

Yes, there are several that look similar. It could be H. androsaemum (Tutsan) which is a native species though the leaves don't look quite broad enough. It could be a sterile hybrid one.

One thing, if it is H. androsaemum, it seeds everywhere with seedlings often popping up here and there in unexpected places.

Thanks.....Has been there a good few years and haven't noticed it seeding any where yet. It has a funny unpleasant smell to it, especially on a hot day or when i prune it.