Hmm..... I don't doubt that the well-engineered BS1363 plugs and sockets (e.g. MK) would carry 16A without any problems, but I don't sede this as a good path to be taking. Let's face it, some of the "el cheapo" contract-range stuff gets warm with a 10A load on it due to poorly designed contacts.
Have you thought about writing the supermarket and explaining that the BS1363 specification doesn't cater for over 13 amps?
