@Lancs Lad : You are correct. The Panasonic extension lead has two flat pin sockets on the top and one on the side. I have the original packing for the lead and it comes with extensive instructions but unfortunately in Japanese, which I cannot read. It does come with some pictures and other information. I will post these here later for those who might be interested.
The lead is very well built with safety markings on the cable, perhaps similar to BSI standards. I was able to open it and take a look inside. There is no provision for earthing and no fuse but the wire is high quality copper. So it would not pass UK safety standards but maybe acceptable in Japan for use with limited devices.
I don't exactly remember whether they had an earth pin in the hotels but they must have had because there were hairdryers in the room
