I don’t know what they’ve done but it looks like it only exposes the extra image size on certain pages.
I’ve cheated and added the custom sizes to my theme since wordpress saves thumbnails by size rather than size-name – in this case 160×160 and 200×200 so when running the crop, the correct file(s) are overwritten.
Thanks for your help – a lot more useful than the response I got from BWS (which was pay us to fix it!)
