The 12v in the boot is a permanent live without the keys in ignition bud. Stops someone nicking your car while your behind it using the 12v plugged in item.
I have read multiple times on this forum, and others, that it is 100% a switched live, it doesn't make any sense
There are two wires going into the 12 at the rear, I think you attached it to the wrong wire- attach it to the other one
I believe the other wire is just a ground, so is useless for this.
There's a spare spot in the fuse box that's igg live.
Thanks, I knew of this already but the 12v supply in the boot seemed easier, but I may have to go for that option now