How can I attach cable clips to an outside wall?

Question

I have plenty of cable clips that work great indoors, but I want to attach a cable to an outside pebbledash wall. The existing cable clips, which have broken, appear to have been nailed into some kind of plug, but I can't see what.

What is a good technique for attaching cables to a wall that won't accept a simple nailed clip?

Answer 1

The original solution turns out to be bits of hardwood doweling inserted into the wall, with the cable clips hammered into them.