Replacing a bayonet type light fitting?

Hi, similar problem. I am replacing a light fitting. The old one had 2 black wires in one hole, and 1 red wire in the other. I am relacing with a 4 hole fitting. One of these holes says loop, one says earth, the oher 2 say nothing. Which hole should I put the black wires in, and which hole for the red. I have tried a few combinations already, but no luck.

Thanks,

Kelvin