Just a comment to that ... if anyone IS adding a UK Socket with a switch (so I am guessing a domestic style socket?) you can get DP switched sockets at just around the same price as SP switched sockets. I try to remember to get those generally anyway purely as they are safer.Germany NOW use the same standard as us, they used to have a weird colour scheme that was Black brown and green I think.
I would check that the blue doesnt continue through out the van as live, ie check a socket wiring.
In reality it probably wont matter as the sockets in the Hymer will be double pole sockets that both L&N are disconnected when switched off. UK sockets only switch the live so in british vans it does matter.
Unless you have added some UK sockets!!??
I suspect that you will just be able to swap Blue and brown over and it will be wired correctly but do carry out the socket check first.
It does matter. The fundamental problem with the British system is that plugs have a fuse. A fuse is inherently single pole. It is important that the fuse is on the live side. If a fuse blows and it's on the neutral side, the rest of the wiring is still live. Non-British plugs don't have a fuse inside, they rely on a 16A double-pole breaker in the consumer unit. The British system uses a 32A ring main, so all the appliances need fused plugs.If everything else is spec'd and wired correctly, it shouldn't matter either way. Note that when you plug into a lot of European hook-ups, it's not a given which side will be live.