I changed my mind - I checked and the blue spots can look white or be hardly visible, so this ID is most likely. If someone has a better idea, good on them! NB: I'm away for 5 weeks from Friday, so unlikely to be doing IDs until late August...!
Nice pics, but I don't think it's this species, which has blue spots across its back. At the moment I would put it in the family Bothidae, but will need to do some more digging. It's similar to Bothus mancus, but probably not that species either....