thanks bob, will give them a tryHi all, back off hols, I would try firstly a mild alkaline generals tone cleaner If you have one, dilute as instructed, test with awhile pad
you could also try a midew product, us hg ltp do one this can often take an organic stain away, need to test , or if an oxide, a NON ACIDIC ( we have rust ex) rust remover may be a possibility . May be a problem on polished