I would strongly agree that colonialism and the fact the British Empire stretched all over the globe account for much of the inclusion of foreign words into English. Another factor is the British upper classes' education in Latin, Greek, and French, as well as other European languages, which pulled words from those tongues into English. English is the largest language in the world in terms of the number of words it contains. Unlike with French, there has never been an academy to keep the language pure and pristine.

However, Orwell is not concerned in his essay about where the foreign words or phrases come from. He criticizes their use because he says they are added simply to make a writer sound cultured, stating:

Foreign words and expressions such as cul de sac, ancien regime, deus ex machina, mutatis mutandis, status quo, gleichschaltung, weltanschauung, are used to give an air of culture and elegance.

As you will note, the words Orwell lists above have not been brought into the language from colonies such as India but from Latin, French, and German. They are meant to parade the writer's education, while obscuring the fact that he or she has nothing of real value to say.

Orwell also notes that the Latin and Greek words are often longer and more ornate than simple Anglo-Saxon words, so writers use them to sound "grander" than they would if they employed a simpler term.

Orwell does not object to foreign words introduced into the language but to their misuse by writers in pretentious ways. Like most people who write about writing, he always prefers a simpler word to a more complex word because he believes that makes meaning clearer.