They stump sprout very easily, in my experience, but I have never seen one grow tall and spindly like this one either. Did it used to be "immersed" in another bush, Sbg? I would give it a dose of blood meal or fish meal, plus a little Epsom salts, to try to bring out some basal sprouts before major pruning.

I have a couple of these - Silver King & Silver Queen. I rarely ever touch them because they can take years to recover from a hard pruning. They are very slow growers.

In my opinion, if you want to keep it, then I would take the top third out and drive a stake in and try to tie in and straighten the stem. Although if you think it is growing in a prime position in your garden then perhaps replace it with something more pleasing.

Thanks for the suggestions. It is under the beech tree and leans at a 70degree angle [ from the soil], so not that far from upright! I took the picture with my back to the tree. In front of it is a sarcoccocus. I like the green and white foliage as it lightens the darkness under the beech.
It does get fed regularly so I think I might see if I can straighten it up more. There are some all white shoots too that make an interesting contrast. I know they don't make their own food but it is interesting.

They need at least a half day of sun, so it could be leaning for the light.

It definitely is leaning :o) as this is a very dark corner.

I'm sure it would make a standard in the right position with a strong tall stake and the untidy lower branches removed, but in that position it might still want to grow lopsided. They are pretty tolerant plants. Two years ago I moved a prostrate one which is 13 years old (from a cutting) and am training it to be vertical but it takes a long time. Unless the space is needed for something else I'd give it couple of years and see if it will grow straight now if you stake it. I have a row of them under a north facing wall where they get afternoon sun in summer and none at all in winter and they are fine. You could always risk moving it but if you want it for the variegation under the beech that's perhaps a bit counterproductive.