Hi Richard and welcome to GoY. The shrub has probably pulled away to get more light, if this is the case it will keep doing so.

Agree with previous answer - unfortunately, it was planted too close to the wall in the first place. When planting shrubs or climbers, they should be a minimum of a foot, preferably 18 inches, away from a wall or fence, otherwise, this is what happens. I can't tell what the shrub is (Camellia maybe?) but perhaps its time to remove it and replant with another plant altogether, preferably something that doesn't have such a rounded growth habit - that narrow border isn't wide enough for such a plant.

It's lopsided and asymmetrical. It will not grow to where there is no sun. This is a shrub and not a clinging plant that uses a wall for growth and support. The bottom is getting long and leggy and in the not to distant future it will bend over completely in a heavy rain or ice storm. I suggest that you take it out and replace it with something like a climbing rose if you have the light exposure for that.

With a marvellous wall like that I'd have a couple of cordon fruit trees and a clematis or even a Hydrangea petiolaris.