It would seem you've got the white core going to the neutral of the lampholder, and the blacks going to the live of the lampholder.
White is switched live,
and the blacks should be the neutral.
This shouldn't cause the RCD to trip though.
Make sure there are no wires shorting together, or against any metalwork like the conduit/fixing screws.
The connections that i posted where the ones i wrote down when i first disconnected the lights. Once i find the fault i'll re-terminate white (switch live) to live of lampholder and black to the neutral of lamp holder
Thanks