In reply to lewismansell:
Wire wool mate. I love my aging JB and found that if any water is left in the pot after brewing up then when you stack the gas and burner head back inside the bottom rim of the gas has rusted and stained the bottom of the pan, wire wool cleans it nicely. Now I simply run the burner for a couple of seconds before putting everything back inside it, this will evaporate any water leaving it rust free next time.
The JB isn't the best for cooking though, look out for instant porridge in the styles of pot noodles next time
Post edited at 11:17