The pins of the UK kettle connector seem to be 5mm in diameter rather than 4.8 (Schuko) but that's not much of a difference.
I don't think they actually fitted any kind of safety cutout unless there's something like a thermocouple inside the element which shuts off power at say above 120 degrees.
The IEC hot appliances connector is slightly different, it'll fit a computer, but a computer lead won't fit a hot appliance since it lacks the side notch between the line and neutral terminals.
I have to correct my last posting, the old "iron connector" had 6.5mm pins, not 5mm (measuring the holes of the female connector is easier but gives false reading). Pretty easy to tell why Schuko plugs don't fit too well. I even have an adaptor which converts an iron lead to an ungrounded extension lead (6.5mm pins and 4mm holes).
Some slide projectors had a predecessor to the IEC plug with parallel flat pins and scraping earth contacts.
Switched iron connectors were fairly common for vacuum cleaners without an integral switch, heat dishes and other appliances. Replacements are hard to find but still in production. I'd like to know why it has been phased out, perhaps due to the overall size and the fairly large holes.
