1/4 cup bi-carb
1/4 cup white vinegar
1 tbs (or thereabouts) of dishwashing liquid
Few drops of eucalyptus oil (to cover up the vinegar smell, but you can use whatever you want really)
Fill the bucket with hot water and hey presto.
I went through about 4-5 buckets of water just mopping our downstairs (upstairs is carpeted thank God!) and the bathrooms. It took me at least 2 hours, but I could literally see the dirt coming off as i mopped. We've had massive issues with these tiles since we moved in as no matter how often I mopped, they were never clean. They're like dirt magnets.