Posted: 09/06/2015 at 10:33
Hi Tabbyfa and welcome - I'm afraid that your honeysuckle has got Powdery Mildew - very common and need not be terminal
The problem is that honeysuckle, being woodland plants, like to have their roots in cool damp soil and their heads in the sunshine. In Homebase (and in many garden centres) the honeysuckles are in fairly small pots in the sunshine and their roots dry out - we buy them and bring them home, and it's only then that the ill effects of the time spent in Homebase etc begin to show themselves ... possibly it may have dried out a bit at your place too ... it happens so easily ... my new one succumbed last year and looked very sad for a while. The drought weakens the plant and it is then attacked by the fungus that causes the mildew.
Just make sure it's in a large deep pot out of the sun (I find that a mixture of John Innes loam-based compost with some ordinary multi-purpose compost added at a ratio of 2:1 suits a container grown honeysuckle quite well. Pick up the fallen leaves and put them in the bin and as long as the roots are kept moist (not sopping wet) it should make a full recovery. If you think it looks really ugly at the moment you could cut the plant back to about 12" above the ground - it'll soon throw out some new shoots and cover that wall for you
If you don't mind using chemicals you could also use a fungicide - details here https://www.rhs.org.uk/advice/profile?pid=253 but don't use one containing an insecticide as it can harm bees and other pollinating insects that will visit your honeysuckle when it flowers.