And Amazon UK CS have just got back to me by email, missing the point completely, and kindly explained how I could manage my content to free up space on my device
They rep has confirmed that 4GB memory is a new feature of the devices currently sold . I just find it strange that it's not officially listed anywhere in the specs, and obviously there has been no announcement of a new model. So yeah, if they're going to do those kinds of improvements silently and late into the release cycle then I won't be buying any future model in a hurry then.