I've only taken up BIR-style cooking in the last year or so, but I definitely didn't fancy the stuff they put into powdered food colouring.
I made CA's pilau rice yesterday and I thought that I had to add food colouring to make it more visually attractive. Instead of powder, I bought Asda's liquid red, yellow and green natural food colourings from the baking section and, I must say, they worked a treat.
I also made tandoori chicken and, although the outer flesh certainly turned out red, I can't say for certain that the red food colouring worked well for the chicken as the marinade was red anyway.
But the rice turned out brilliantly, and I would certainly recommend the Asda food colourings for pilau.