iPhoto data in my iCloud account

I recently had some major space issues with iCloud and had to spent the night cleaning out my Mac and Mail to create enough space. In doing this, I have found that 2.1Gb of my 5Gb allowance is taken up by iPhoto data, but I can't tell what this data is, where it is coming from or how to reduce it. Can anyone shed any light on this?

Below I have taken a screen shot of what I see in the Manage Storage window. To clarify, I have uninstalled iPhoto from my devices, I have sync'd and deleted all the images on my camera roll. I have deleted a bunch of photos from My Photo Stream just to check (even though all the literature says My Photo Stream does not count toward iCloud data storage). So I am at a loss, I am hesitant to delete this data without knowing what it is, but at the same time I can't find what the source is to verify that it is not something I want to keep.

Any ideas appreciated. Thanks