@jonasgraphie @franckraisch @EUCommission The 2-wire europlug can also be inserted into a UK outlet without an adapter; simply insert a prong into the hole for earth/ground and then the shutters open for live/neutral. You can then shove your europlug into it. I've attached the relevant photo showing which cable i mean.
Obviously, doing this is not recommended in practise, but it does work.
UK outlets are designed that way. The live/neutral shutters only open when a prong is insert into ground.