A leaf of holly (Ilex aquifolium) with black spots. This above image shows the upper surface of the leaf, the image below shows the lower surface:
Under my stereo microscope most of the spots on the lower surface had a small hole at their centre and in a couple of these holes contained what looked like an insect egg:
Note added 2014-05-04: The black spots might be the fungus Coniothyrium ilicis. As not all of the spots have holes in them it is probable that the egg-laying insect deliberately selected the fungal patches in which to lay its eggs, presumably because the leaf surface was weaker there.
Specimen taken in Whiteknights Park, Reading, UK, on 2014-04-12.