“It’s very apparent that her tiny bit of Hollywood fame has gone to her head,” Mr. Markle wrote. “To top it all off, she doesn’t invite her own family and instead invites complete strangers to the wedding, ‘who does that.’ ”

Kensington Palace offered new details on Friday about the wedding, though they were not necessarily the details the journalists present were hoping for. (Examples of questions left unanswered: “Will Meghan Markle’s family be given a coat of arms?” “Will we get a kiss?” “Is it in your power to alter the Heathrow flight path?” “Can you provide any information about whether the princes will do an ‘impromptu’ walkabout the day before?” “When are we going to get that snog?”)

To most of these, Prince Harry’s communications secretary, Jason Knauf, promised “operational guidance” closer to the wedding, as if the journalists were preparing to embed with military units.

It emerged that Ms. Markle would not have a maid of honor — “she has a very close group of friends, and she does not want to choose one over another” — and that her bridesmaids, in accordance with royal tradition, would be children. Her parents, upon arriving in London, will be introduced to the queen, the Duke of Edinburgh, the Prince of Wales, the Duchess of Cornwall, and the Duke and Duchess of Cambridge.

Prince Harry has spent time with Ms. Ragland, and was reported by People magazine to have asked her permission for Ms. Markle’s hand. His first meeting with his father-in-law will be the week before the wedding.