Interesting takes from you both. This could lose focus, but I do like historical discussion :)
I think you both have valid points on the historical aspects vs. game play realities.
Britain’s and France’s alliance, at least in the form we know it as it concerns WWII, stemmed in 1938-1939 after the Munich Conference. The alliance was really geared towards stemming German/Italian expansions in Europe. I don’t think Japan/Asia was really much of a thought or concern. That probably stems from a number of things, a couple being a contemporary belief in Japanese/Asian inferiority (even with Japanese military success in the recent past), as well as being largely unaware that Japan would eventually harbor the ill will to fight the Allies. They didn’t join the Axis until 1940, remember.
That’s all to say that I agree with GHG, in a historical context, that Britain and France were more concerned about issues closer to home.
All that said, from a gaming perspective, I do agree with Dran here. In a hypothetical reality where Japan preemptively assaulted the British Empire in Hong Kong, Malay, Burma, India, etc., I think it’s very obvious France would have gone on high alert, fully realizing their Indochinese colonies might all of a sudden be in jeopardy. We of course cannot know this, since Indochina was occupied after a Vichy government took control. But I think reason dictates there would have been a heightening of fears in the French Empire.
In that regard, it would have been nicer to have seen a bit more of a peacetime income increase for a situation like this, I agree. But at least there is that +1 IPP for Japan attacking a Neutral UK.