Found dead in some dust in a seldom visited corner of the house!
No interactions present.
If still have it and can expose the underside of the hindwing a bit more it should be possible to be sure of the ID.
It looks here like the copper does extend beyond the cross line which would suggest Svensson's CU but I'm not confident that is not just a shadow in the image.
I haven't got it any more, but the hindwings were completely orange (or what I saw of them were). Does that make it a Svensson's CU?
The upperside of the hindwings (which I suspect is what you are referring to) being completely orange is true of both. The underside of the hindwings being completely orange is true of neither. You would need to have looked at the underside of the hindwing and determined whether the orange on the trailing edge extended all the way up the wing.
Lat/Lng: 51.7, 0.4
OS grid ref: TL7006