Victorian floor tiles, both originals and reproductions, are usually similar in structure to regular modern ceramic tiles. The main difference is that Victorian tiles usually have intricate surface designs painted or printed on the surface. This makes it especially important to assess and adjust the layout of the tiles in advance of mortaring them down, to ensure that the cuts aren't going to interrupt the design in ways that are unattractive; for example, cutting off a drawn flower so that all you see is the stem.
Use a chalk snapline to snap two perpendicular lines over the middle of the floor, dividing it in four. Put a square at the intersection of the lines to ensure they are square against each other, adjusting the lines as needed.
Lay your Victorian floor tiles out along the lines without mortar, putting spacers between them. Assess how wide the tiles at either end of the floor will be. Measure that span on a tile to assess whether the cuts at the edges of the room will divide up the surface design in ways that will look bad. Adjust the lines in one direction or another, as needed, until the designs at the edges of the room are satisfactory.
Take up the tiles. Spread thinset mortar over the centre of the floor where the adjusted lines intersect, using a notched trowel.
Set the first tiles in place at the intersection bordered by the two lines. Put spacers between them.
Spread more mortar around the tiles and lay more tiles, working your way out on the lines and building into a grid pattern. Cut the tiles at the edges of the room as needed with a wet saw.
Let the mortar set for 24 hours. Pull out the spacers. Grout the floor with a grout trowel, squeezing the grout into the spaces and wiping up the excess with a damp sponge. Let the grout set for two days before you walk on it.