You really can’t use Left-Wing Guardian articles as proof of anything: it is a Socialist propaganda paper. The Author argues that Colonial Imperialism was based on White Racism, and helpfully points out that Hitler was a racist too. No shit, Sherlock!
Svetlana merely points out the obvious truth that not all Empires in History were run by White people, and it is racist to suggest that White people are more racist that other races.
I’m not sure “White” is even an accurate term: it is a colour, not a race. In my opinion, Asians are whiter than Europeans, who seem to me to be pink, not white. But then “Pink Supremacists” wouldn’t have the same ring to it, now would it?
Finally the British have one claim to distinguish themselves from other Imperial Powers: they voluntarily gave up their Empire, granted independence to all their Colonies, and did so without warfare, except for America, which fought a War of Independence largely to stop the British granting the Plains Indians British citizenship. They also abolished slavery, and used their Navy to catch Slave Ships leaving Africa, freeing the surviving slaves in Liberia. So while there were racists in the British Empire, the Empire itself did not always act in a racist way. The British have their faults but also have much to admire in their History. You wouldn’t know that if the Guardian is where you get your “facts” from.