Thanks all for the comments!

To clarify a few things:

All 4 pickup wires are single core

Bridge = Red and Black
Neck = White and Black

I have a picture of the pickup setup when it arrived.
Click image for larger version. 

Name:	IMG_20191208_092505.jpg 
Views:	1336 
Size:	136.2 KB 
ID:	32980

I've removed all current work, and reverted back to the state where I have done no additional soldering. Also tidied up the wires as advised. Picture below (let me know if you need a higher res)
Click image for larger version. 

Name:	IMG_20191210_182636.jpg 
Views:	1292 
Size:	270.1 KB 
ID:	32981