If the value is over £390 then yes. Currently (and dont think it will change any time soon) the 16GB and 32GB iPads fall under that category as the 32Gb is around £388 (without sales tax).
But to be on the safe side if you put it in your hand luggage you would be fine![]()
But how would they know he bought it whilst there? If it is unboxed etc, he could have taken it to the states with him, right?? In which case he may have already paid...
Not sure how this works...