warmth and humidty. typical at this time of year. you can get a fungicide to spray on your plant. a more open structure that lets air circulate will also help reduce infection. collect all the fallen leaves and burn or put in the household rubbish. dont compost the leaves as you will only keep the fungal spores for next season.

Thanks Seaburngirl, thats a great help. I have another honeysuckle on the other side of the garden, is there danger of it spreading?

theoretically yes. but if you spray them too as a preventitive measure.