Thanks very much for all the replies and explanations. After a few of you explained bending metal one way and then the other in a home made bender I realised a still have a home made bender that I borrowed from someone. It is a effectively two square section bars bolted together with a slight radius on one edge. I have used it for simple bends but didn't think to use it for the double bend, I think I was so fixated on bending the metal over a pipe or using the existing metal bend on the vehicle to shape something.
I had a go and it seemed to work better than I thought, I used a wide chisel and hammer to aid in the second bending and then used the vice to flatten the bend until it was more of a sloping double bend rather than too rigid and straight. I know some might consider it a bit rough but it seems to have worked okay.