Rear camera wiring ford fiesta 2007

[Midge8209]

Hello, I am trying to wire up my rear camera to a ford fiesta Mk6 2007. I use to have it wired to a Renault Clio MK2 by connecting the wire to the reverse light wire and so I was hoping to be able to do that again. So I took of the rear light and I have 2 different colours coming from the reverse bulb, a brown and a black. I think the black is a live but not sure. Do I connect it to the black or the brown? I know a lot more about clios than other cars but I know the basic goes with all cars but wanted some reassurance.

Thanks all

[Paulkp]

Haynes manual shows Bk as ground