iCloud.com photos wrong date and time

I have uploaded around 1400 of my iPhone photos from my Mac to iCloud.com, but almost all of the photos have the wrong time and the wrong date.

What's even more strange and annoying is that I went back to see my Photo files in my Folders in the Finder to check the date and now they are all messed up too!!

A huge chunk of them have Date Created/Modified/Opened on Friday 10th July 2015 13.15 - which doesn't make any sense!

Is this a bug? It seems to have made it's way from iCloud.com to my computer? Anyone else have this problem?

Thanks for any replies

L