ets being upside down. From memory it is not allowed for safety reasons. I = think it was because the earth pin may disconnect before the other two pins= .
I do remember that item, many years back involving that issue. An electrical inspector pointed this out while checking an installation IIRC. I think the sockets in question were a special setup for disco lights or something "controlled" like that, not for a regular power socket.
One thing I have noticed with some Chinese plugs on imported equipment is that their earth pin seems to be longer than ours even though the plug is otherwise the same. If it is a bottom entry plug, usually the entry will be on the top. Same with my Nokia charger, the pins seem to have been put on it "upside down" so that when the charger is plugged in, the body of it covers the switch on a typical Australian single power point
Even though the UK has a different plug, their earth is also at the top on a typical power point.