Thanks for the reply's guys. I have just de-soldered every thing and checked as I re-assembled and it is still there. It is more noticeable when the volume pots are turned up full.
It has a MM humbucker at the neck and a Jazz at the bridge, Two volume pots, one 3 way switch..
The only thing which was constant in the re assemble were the jack socket and lead, and I am 100% certain that it isn't the lead.