Yeah that was probably deliberate. A lot Canadians are very cynical about British colonialism considering we are a direct product of it. It probably because a lot of us wound up here because colonialism screwed things up so much worse where we came from. The Clearances in Scotland, The Famine in Ireland, Opium in China all the way up to Partition in India. Even most of English immigrants to Canada were from the lower classes and were exploited by the English system. So yeah Murtry being a posh dick was probably a deliberate choice by the Canadian casting director. I do wonder what the actor thought about it.