Pedigree breeding and diversity.

And let’s not forget the Musk roses which bloomed throughout the year. according to Roxburgh (1813). These were in India before the Rose Edward was mentioned, but I don’t know when they were introduced.
http://bulbnrose.x10.mx/Roses/breeding/RoxburghIndica1813.html

I don’t know when the Kakinada Red reached India, but I find no mention of it in the early 19th century reports. It is important to remember that some roses (and other plants) become very popular and are distributed so widely that later writers assume that they had a long history in the region. This was certainly true of Rosa laevigata, which was cultivated in Georgia by the second half of the 18th century (before the American Revolution), and was then distributed (as a hedge plant) so quickly and so widely that later writers assumed that it had been naturalized at some remote period.

Richardson (1855) wrote, “The Madras rose, or Rose Edward, a variety of R. centifolia, Gul ssudburuk, …is the most common, and has multiplied so fast within a few years, that no garden is without it; it blossoms all the year round, producing large bunches of buds at the extremities of its shoots of the year; but, if handsome, well-shaped flowers are desired, these must be thinned out on their first appearance, to one or two, or at the most three on each stalk. It is a pretty flower, but has little fragrance.”
http://bulbnrose.x10.mx/Roses/Ehret/Richardson1855.html

Karl