Assess what is on your Victorian tiles.
First you need to assess what is on the tiles to know how to tackle them.
Original waxes but dirty: If these Victorian tiles look dirty grubby , but with little or no shine then you are in luck as they are likely in their original state with natural waxes inside them. These are easy to clean and the waxes have protected the tiles over the years.
Polyurethane coatings and acrylic wax polishes: Here’s where cleaning gets more difficult usually. If the tiles look shiny or have an obvious sheen there is likely something coating the floor. Sometimes these coatings are acrylic waxes and sometimes they are polyurethane varnishes. In any case, this shiny coating needs to come off completely as it will interfere with the finishing process and if any bits of the coating are left the cleaning process may cause them to discolour and go white. These coatings can vary in difficulty to remove but with enough effort you will eventually remove them.
Obvious cement Screed material where tiles have had other tiles over them: Often beautiful Victorian tiles have been tiled over with less attractive tiles. When removed they leave allot of cement residue and chunks on the tiles that need to be removed with scrapers and chemicals.
Glues and adhesives: These can vary in difficulty to remove. If they have been used for carpet grippers and have a greenish / yellowy look they are fairly solid and can usually be loosened and scraped off. If they have been used for vinyl floor coverings and are bitumen based they are very hard to remove and damaging to the tiles if not done properly. Glues require more mechanical action with scrapers usually before chemical deep cleaning can work.
Very porous untreated Victorian tiles: Where people have applied acids and left them without neutralising them these tiles seem to get more spongy, porous and become harder to clean as you can not create a proper chemical water slurry mix. Abrasive pads also degrade the surface of Victorian tiles.