Why have my deleted iphone photos came back?

I've just gone through my photo album and I've just realised All the photos that I've deleted over the past few months are back on my phone. I just deleted them all again but how can I make sure they are deleted permanently? It's so frustrating!

Have you plugged your phone into iTunes lately? They are probably backed up to your computer and re sync on your phone when you plug your phone in.

The photo album has synch'd with the cloud backup.