I have stripped the taps down, and these are the results.
As a temporary measure, until a permanent solution is sorted out, this is what I have done.
I used a dowty washer, followed by a nylock nut, followed by a copper washer, thus, They look a bit weird, but they don't leak anymore.
I will have a word with my good mate Dave and see what can be turned up on the lathe. Then I can book that M.O.T. again.