I forgot to say that I got version 5.4 working by overwriting the shaders/private folder.
However I needed to run the following console command for it to appear correctly.
r.DefaultFeature.AutoExposure.ExtendDefaultLuminanceRange 0
However, as stated in the previous post, I feel that the diffuse input is being darkened even in light and with light parameter set to 1,1,1,1