How do I open this ?
It's a non-rewirable plug, so it doesn't need an earth pin. And indeed it does not have one - that is an insulated shutter opening device.I see it has a plastic earth pin.
Right, it's as I suspected.
Is this really the first plug like this you've seen?
I'd imagine they're more common, when supplied with appliances, than "traditional" plugs.

Is there a way of opening it or not ?

I'd just cut it off and start with a new plug

Sorry should have qualified that with "if there was a problem with it"Why would you do that? He hasn't said that there's anything wrong with it.
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