Consider how the borders were drawn and how peoples were moved about in different instances of British colonial rule, and you'll see that the roots of many contemporary conflicts are indeed born of British practices of divide-and-keep-divided. How did the Tamils wind up in Sri Lanka in the first place? How did Iraq, such an unstable mix of cultures and constituencies, wind up lumped together into one unit, with the Kurds split in half? How about Sudan divided against itself? Partition in India? It just keeps going.
John Bull isn't responsible for all of it, though. The French did a fine job of their share, too, and Uncle Sam got his hands in the mud as well, &c.
Great reading: The Many-Headed Hydra, by Linebaugh & Rediker, shows the history of some of this in the Atlantic world.