Please see attached photo. This is the wiring in our bathroom. I've just removed the light fitting that was installed when the house was built and this is what is behind it. It doesn't look right to me. It appears the original fitting was installed using the black, blue and grey wires, but I didn't take proper notice of how as I wasn't expecting to see something that appears to me to be non-standard. Does anybody have any idea why this would be done in this way? Is it safe? Can I just wire up a new light fitting to those wires? Thanks in advance.