Hi Anna, this was also posted in another area and I think you have opinions given there.
However, I will let you have mine. It's definitely canine rather than feline as felines have retractable claws that rarely show up in footprints. It looks like a footprint I a piece of terracotta, Roman perhaps? These are often attributed to fox, but I feel they are just as likely to be domesticated dog hanging around the terracotta yard and leaving their prints in the undried tiles.
Here is a picture of similar that I have taken which came from the Roman fort of Calleva - now Silchester in Berkshire.
For what it is worth here is a thought. The depth of the footprint should give you an idea of the weight of the animal. If we consider the consistancy of the drying tile to be fairly firm the the depth of the paw print may suggest a dog. If you can get your hands on some plastercine roll out a square and get your local friendly Labrador to step on it.Hope that helps.