Indeed, thats a mitigating factor, nostalgia like that breeds ignorance. But when you are directly faced with the obvious facts of the centuries long fucked up shit your ancestors did, and still ignore as a minor thing or half assed acknowledge ("oooh it wasnt so bad, what about all those acheivements..."), then thats something else really. Desperately trying to semi-justify massmurders and such with saying "we brought them alot of good" is really fucked up either way.
But atleast brits arent remotely close to the Japanese (or italians relation to faschist past), who completely and utterly collective brainwashed themselves in the fucked up horrors they are guilty of (they dont even have the excuse of being centuries ago and hard to relate to today), they frigging upstaged the nazis with some of that shit. But ask one of what happend in Nanking, and you will be in utter disbelief the response you will get...