Ok, but the Nazi obssession in GCSE curriculums is questioned all the time, by conservative critics (the people trying to put Empire back into the curriculum) more than liberal; actually liberals are usually fairly happy with GCSE history, which is an astonishing position to take if ever there was one, as it is obviously a disasterous waste of time.
When I was doing GCSEs in the mid-90s, the British Empire certainly was part of the curriculum and did not glorify or endorse it in the slightest. In fact, Roberts and Niall largely write in response to the opposite senario, a perceived left-liberal cultural assault on British history that takes place precisely at school level.
My GCSE course put a heavy premium on "bias" and "propaganda" and knwoing how to spot it, who uses it and why; we learnt more about that than any actual history, from what I remember.
In my lifetime, the mainstream mood has not been smugness about Empire, it's been a glorification of deteating tyranny and reverance for the fallen of two World Wars; whatever you think of that (and it's more extreme now than, say, 10 or 15 years ago), it's a different thing.