Thanks
I don't really know, exactly. It's not a lino or wood or any soft finish like that. Its an internal communal corridor, bit like supermarket flooring I guess, concrete then screed with some sort of sealed finish. The polished seal has long gone. I've tried cream cleaners with scouring pads, bleach etc. not budged yet. Kids do wheelies and whetever else with their bikes, up & down the corridors