First line of this chapter: "Mrs. Ali left the village" (18.1). She doesn't even say goodbye to the Major. Ouch. That has to hurt.
The Major gets a cold and has to deal with Christmas™ and all the non-stop marketing that goes with it at the same time.
When the Major gets over his cold, he heads to the village shop where all the handmade things Mrs. Ali normally has on display have been replaced with cold, corporate awfulness. And Mrs. Ali has been replaced by a mean old woman who sits behind the counter with two scary-looking knitting needles.
Abdul Wahid says hi to the Major and returns the book of Kipling poetry he lent to Mrs. Ali. Double ouch.
The Major goes to church, where, at least there isn't awful music being piped in 24/7.
It's not the Christmas miracle he hoped for. A conversation with the vicar concludes with the vicar admitting that he's glad Mrs. Ali moved. He'd hate for the Major to have married her, because there's that whole issue of "theological incompatibility" (18.45).
With nowhere else to turn, the Major goes to Grace's house, and she invites him in for tea. They have a nice conversation, and the Major invites her to Christmas dinner at Roger's.