There are others with the same number of petals but if it has more or less presume you can rule it out. I was unaware that a parpticular rose always had the same number of petals.
My husband thinks that his mother brought the rose with her from London and that her father had it as a cutting from somewhere he worked.
I think it has gone out of favour because it is rather rampant and also newer varieties are bred to have a longer flowering period.
My daughter lives in the house now so I will ask her to also count the petals.