The entire British Empire declared war on Germany because of its invasion of Poland. That includes Australia, Canada, Fiji, India, New Zealand, South Africa etc. Then in 1945 Churchill agrees to hand over Poland to Stalin yet the MSM still like to refer to the former British leader as a "great statesman". Nothing could be further from the truth. Even the History Channel has come out with a documentary on how Churchill stabbed the Poles in the back -
Indeed and even, if you assume that the pretext was legit.
I'd assume most British had no clue on how the Polish-German war was engineered to create that pretext. Neither did the people in the Colonies, or rather dominions. Because that would require a decent study of previous history, diplomatic record, sequence of events AND on what covert operations would have been up and running. The later would be dismissed as "conspiracy theory", but given the presence of British Intelligence Operatives in Poland prior to 1st September 1939 it's worth investigating.
By creating a distraction the Allies tacitly admitted that there was a legit casus belli for the Germans. That Naujocks statement they got is more then just dubious. And the British viewed Naujocks with suspicion themselves. It sounds much like projecting. Ironically Hitler never used the Gleiwitz incident never for the purpose of justification. The German media printed another narrative about events elsewhere.