[The Major] didn't like being driven by a woman. He hated their cautious creeping about at intersections, their heavy-handed indifference to the nuances of gear changing, and their complete ignorance of the rearview mirror. (1.80)
The Major is a traditionally crotchety old man, but at least he's a somewhat open-minded one. He may not like being driven by a woman, but he makes an exception for Mrs. Ali, and he keeps his mouth shut about his preconceived notions. She defies them, anyway, which gives him a pleasant surprise. In this case, he's glad to be proven wrong.
[Sandy] left a trail of perfume in the air. It was not unpleasant, he thought, but it hardly offset the appalling manners. (2.51)
There are many things about Sandy that the Major finds rude. Her fragrance is one, but her general Americanness is viewed as less than classy.
"We need to avoid even the semblance of any dishonorable intentions. There are liability issues, you understand?" (4.84)
You've heard of the British being very mannered. When it comes to the dispute over the guns, the Major's attorney believes that he shouldn't rock the boat. It would be beneath everyone to make an issue over a couple of rifles. Strangely, selling the treasured guns for money isn't seen as tacky at all.
[The Major] had never felt animosity toward those who were born into great social position. (5.15)
Speaking of not rocking the boat, the Major is perfectly fine with the whole British class structure situation. Is it easy for him to accept it, considering that he's upper-middle class? He gets a pretty sweet deal, after all.
[The Major] was sure he could talk up his lordship to the heights of an earl and impress upon Marjorie the privilege accorded the entire family by the invitation. (6.131)
The Major knows that his brother's widow is impressed by class, so he plans on inflating Lord Dagenham's title, which will make it seem like he has more money and like he's a more desirable person to sell the guns to.
"Why, Jasmina, you are here too?" [Mrs. Khan] asked. The Major recognized the use of Mrs. Ali's first name as a deliberate slight, but he was grateful to finally hear it. It sounded enchanting even from such a raw and ill-intentioned source. (9.70)
Mrs. Khan intends to position herself in a higher economic class than Mrs. Ali by being the first of them to fling out the other's first name. This is disrespectful; in this context, it's as if Mrs. Khan is speaking to the help—but that's pretty much how Mrs. Khan views Mrs. Ali, who runs a lowly general store.
"I suppose I'm not as important as your friends? And since when did you count shopkeepers as friends? Are you best friends with the milkman now?" (10.84)
Roger is aghast that his father has made friends with the help. Roger believes that people should only hang out with others in their own social class.
"No one tells my son he's a servant, or a 'worker' neither! […] We were asked to help out and no one is going to treat us like dirt." (11.57)
Amina is very sensitive to issues of class. She is both working class and a racial minority, so she is on the receiving end of discrimination for a variety of reasons. Here, she stands up for her own work ethic, and she takes pride in what she does.
"Maybe we should just shoot them," said a banker somewhere down the line. A chorus of approval followed and one or two men leveled their guns at the field. (15.98)
The men at Dagenham's duck hunt feel that they are more entitled to their land than another person is to his or her own life. He suggests shooting a protestor who holds a different opinion. Yikes.
"I'm usually wrapped you half a pound of streaky bacon, three ounces of Gorgonzola, and a half dozen slim panatelas," said Mrs. Ali, raising an eyebrow. (16.84)
The people at the dance don't recognize Mrs. Ali in a fancy gown. They're used to her serving them, and it's hard for them to imagine someone who serves them showing up anywhere as their equal—and in a fancy gown to boot.