Brown wired into 'N' and Black into 'L' on Outdoor Brick light?!?

[Pixelboyo]

Trying to replace some existing Brick lights which have rusted and the bulbs have blown. Anyway, after finally managing to get the thing open, I looked at the wiring and first of all noticed the wires were brown, black and grey - there are 2 of each. Second of all it looks like the black wires are wired into the 'L' slot of the lamp and the brown are wired into the 'N' slot. Seemed strange to me as I've always take brown to be Live. Finally the grey wires were just terminated (would these be earth?). I've uploaded pics to show the wires and the diagram on the lamp to show that the brown is wired into the bit labelled N.

My concern is that the new brick light I want to fit is a completely different and a lot simpler type of light fitting and I don't want to get the L and N wires wrong.

 

[westward10]

I suspect they are swa cables which may or may not be glanded to the enclosures of those lights, if not I suspect they are not earthed and I would ensure you have the power off if touching them.
That is probably not a job for a DIY person as someone needs to assess what is actually going on there.