Check your skin's config.xml file. If I remember correctly, there's a quality property in there where the image sizes are defined.
Thank you for that. In the end I was just working late and when I changed the path to source failed to knock the 270 size off the image. Pictures now loaded perfectly. So if anyone else is having trouble, just upload picture to at least the size you want it to be into a folder in the images file. Change the path from "cache" to "source/your_folder_file_name/" and take off the .270 at the end of the path leaving just your" image_name.jpg" You can then re-size as normal in the picture editor.