Thanks Fender,
It is grounded, it's the black shielded cable that runs right through to the jack. Tested with multimeter and that's all fine. It did occur to me that I hadn't shielded the pickup cavities which I'll try to do today as I do have a roll from the last build where I also forgot about shielding those cavities :-D
That, plus fixing the switch grounding and moving the bridge grounding connection to the back of one of the pots and hopefully it will be sounding better soon.