Thanks again all, I'd be absolutely delighted if it was a Davidia, it would have pride of place in the middle of my front lawn! But, as obviously not so CluelessGardener says the leaves don’t seem to match entirely, they are certainly hairless so maybe var. vilmoriniana? Not sure. The buds look promising though.............
so I have added a close up.
It was bought in a sale from a National Trust shop and according to the incorrect label it was also grown by them in Devon/Cornwall. My neighbours took the photo and a leaf to Wisley last week and also drew a blank, they just confirmed that it wasn’t a Clerodendrum!
I shall have to go and find a growing specimen.