Your hebes are suffering from a fungal disease similar to rose black spot. If you do a Google search, you'll find lots of info on how to deal with it, including this from Helen Yemm (scroll down the page till you get to 'The Hebe Jeebies'): http://www.telegraph.co.uk/gardening/gardeningadvice/3340075/Thorny-problems.html

Is the hebe growing in that tiny blue pot? Time to pot on, I think, or get it into the ground. Stress a plant and all kinds of diseases can take hold.

No the hebe is planted in the ground. What I was thinking of doing is give it a good prune, feed it some fertiliser, and give it a spray of fungal as suggested. Any other ideas ???
Also thanks for your ideas.

Nope, too late for hard cutting back and feeding this year - you may force new growth that won't be hardened off for winter. That'll have to wait for mid to late spring next year, after growth has got going I'm afraid. You'll have to content yourself with a light trim and using a fungicide or the milk and water spray - one part cow's milk to two parts water, mixed up and sprayed till run off all over the plant, as effective if not more effective than the fungicides available anyway. Collect and bin fallen leaves too.