Today there is comparatively open talk about the "Sex Industry" and there is no doubt that it has always been with us, as the description "the oldest profession" suggests. However, when you look in typical family history records there is no mention of it. However there is no doubt from some of the more revealing private diaries, such as those of Samuel Pepys, that women of easy virtue were very easy to find. In addition there were Victorian organisations dedicated to saving "Fallen Women" and vast institutions for taking care of "orphaned" and "abandoned" children.
While there must have been many "on the game" I doubt very much if there were many Victorian marriage certificates which give the occupation of the bride as prostitute. A look at the census (any dates) suggests that the number of households in which a wife or daughter is described in this way is negligible - for instance there are only two examples in London/Middlesex in the 1881 census - and it very likely that the people concerned were illiterate and the census enumerator filled in the form. The vast majority that are identified are to be found in prisons, hospitals. etc., where they cannot have been following their profession, and where the occupation would have been supplied by the institution.
From the point of view of the family historian this is a very difficult area, as in some cases there were problems in identifying the mother (who may have used a false name) and the mother may not have know who the father is.
If you can add to the information given above tell me.