Thanks Irving, saves me looking at the regs but as you say law or not it's not good practice.

So because I have to keep to regs, these are not for me. I have some of the 4 pin military type ones similar to these.

CONNECTOR Picture - More Detailed Picture about 4pin circular connector, diameter 1.5mm*4 ,free shipping Picture in Connectors from Shanhe Electric Co Ltd

But opposite, female in the socket so legal, Again all the ones on the aliexpress site seem to be opposite