Eventually i want to re zinc plate the door catch but for the time being it makes a big difference by just giving them a good clean.
I marked up the position of the plates on the door post before removing them to make sure they went back in their original positions. Then i wire brushed them with a drill in a vice.
I left the door mounted latches in place but used a piece of plastic to protect the paint work whilst a used a hand wire brush to clean them up.
Very pleased with the final finish when done compared to the original black stained oily previous state.