Thank you Tadgh,
For the advise and sample product you sent me, great result on the sample clean today , client very happy and has booked work for all area,s to be cleaned.
pic below if it uploads 
No Prob Geoff, glad that it worked out for you, we had a job recently canteen,hallway,toilet floors, same porcelain tiles as your picture and same problem, they were mopping everyday with kentucky cotton mops and a heavy duty kitchen degreaser (high alkaline based chemical) which was just grinding the soils into the substrate of the tiles, we see this problem everywhere and everyday, but hey it generates plenty of deep cleaning work where you can charge well.
