I feel that this is a major source of why Britain (and Europe to a larger extent) is unable to come to terms with reality on a majority of issues today - immigration, foreign policy, economic policy etc. They simply have not come to terms with the loss of their empires and the wealth they brought. So they choose to not teach it. This leads British institutions today to have a serious colonial hangover whether they know it or not. The operating paradigm is still an outdated one in many cases.
They teach students what they think made Britain great -- the Romans, the Norman invasion, the World Wars, Churchill etc. -- while actually glossing over what made them great: Empire. It really brings to mind a line from the Thor: Ragnarok movie - "Proud to have it; ashamed of how they got it". The British people today might not have an idea of their Empire but the effects still linger on in their former colonies.