"Milk in first and Indian"—what does it mean?

I went to tea with Stella once. Milk in first and Indian.

English tea is served in a cup, of course, and usually with added milk. When Stella served the tea she put the milk in the cup first, not the tea. And the variety of tea she served was Indian (vs the default which I would presume to be Chinese).

I have been reading a biography of le Carré by Adam Sisman and come across the following passage in Chapter 9, which deals with the time le Carré was teaching at Eton College, and I presume Mrs Hecht's words were taken from the author's experience at the upper-class public school:

He [David Cornwell, i.e. le Carré] had been appalled by a colleague's report of an overheard conversation between two boys after one of them had been to tea at Wheatbutts [the Cornwells' home]:

"Had tea with Cornbeef the other day." "How was it?" "Usual stuff. Milk in first and then Indian."

"I don't think I've ever met so much arrogance," David concluded.

Both episodes are based on the premise that not putting milk in first and not using Indian tea is the socially correct way of making tea for the likes of Mrs Hecht and the Eton boys.

It means poor/cheap. When making tea, if you were poor and had cheap, low quality china the hot tea could crack it, so you would put the cold milk into your teacup first to prevent that from happening (as opposed to tea first then milk, which was considered the proper way to do it by English upper class). Tea from India was the cheap stuff, as opposed to better, more expensive tea from Kenya or China. Cheap tea served in cheap china, the poor man's brew.