I have managed to get the thumbnails in the portfolio section of my theme working as retina images, however the smaller thumbnails on the homepage and the main images inside the portfolio section are not showing as retina. I have only uploaded one image which is the correct size for retina so in theory all the images should be shown in retina format.
I don't know whether they don't work in a slideshow though? My site is http://www.jonquayle.co.uk if someone who knows a bit more than me is kind enough to take a look? Any idea what I can do to get this up and running?