text: At a Buckingham Palace garden party in pouring rain on Tuesday, the Queen commented, "Oh, bad luck"  when told a Metropolitan Police commander had led the police operation around the Chinese leader's visit.
  The Queen's unguarded comments are atypical for her, but also pose some unanswered questions about the visit.
  In short, we don't know. Police Commander Lucy D'Orsi was "seriously, seriously undermined by the Chinese", according to the Lord Chamberlain, who introduced her to the Queen.
  Commander D'Orsi said it "was quite a testing time" and that "they walked out of Lancaster House and told me that the trip was off".
  The Queen clearly knew all about the incident concerned and interjected: "They were very rude to the ambassador."
  "They walked out on both of us," replied Ms D'Orsi.
  Did Ms D'Orsi mean that Chinese officials threatened to cancel the whole state visit? Or just part of the itinerary?
  Was any conflict to do with security arrangements (as Ms D'Orsi was clearly under pressure) or of wider diplomatic significance?
  We simply do not know. The police have not issued any statement.
  President Xi and his wife Madame Peng were guests of the Queen and Prince Philip at Buckingham Palace for the state visit so perhaps it is to be expected that the Queen would be aware of such details.
  The Metropolitan Police had to defend itself from human rights groups' accusations that it dealt inappropriately with protesters during Mr Xi's visit in October 2015.
  Commander D'Orsi issued a statement in the immediate aftermath of the visit saying she was disappointed at hearing the view expressed that the Met was "working to the bidding of the Chinese to suppress protest".
  The Queen's comments were picked up by the microphone of the camera filming the garden party event, operated by Peter Wilkinson, the monarch's official cameraman
  His footage was released to broadcasters under the "pool" arrangement which is standard procedure for royal events (to avoid all broadcasters sending their own crews to every engagement).
  It was only then that the uncharacteristically undiplomatic comments were spotted.
  Indeed. At the time Mr Xi said he believed his visit would lift UK-China relations to a "new height".
  Buckingham Palace would not comment on a "private conversation" but said all parties worked closely to ensure the visit proceeded smoothly.
  Chinese foreign ministry spokesperson Lu Kang said the president's trip to the UK was very successful and "marked the start of the Golden Era between China and the UK".
  We now know, thanks to the Queen's comments, that it was a testing time behind the scenes, at least for the police commander and the British ambassador to China. However, that does not mean that overall the trip was not a success.
  Kerry Brown, Professor of Chinese Studies at King's College London, and a former senior British diplomat in Beijing, told the BBC that it was striking that even someone with the Queen's six decades of diplomatic experience still found dealing with the Chinese protocols and machinery tough:
  "In terms of the atmospherics between diplomats in China and the UK, it's not an easy relationship and that comes through in the freight of emotion that was in her comments."
  At the moment, there is no coverage whatsoever of this in mainland China, says BBC Monitoring's China Media Analyst Kerry Allen.
  "This is not unusual. The comments the Queen made will be regarded as highly embarrassing by China's elite, as the concept of 'maintaining face' - one's sense of dignity or prestige - is incredibly important within the country," she says.
  "Owing to the sensitivity of her comments, state media will be required to hold off covering this until the government decides what official response to give.
  "Some users of popular microblogs like Sina Weibo though are commenting on it and quickly gaining responses. However, the censors are catching up and censoring comments to limit impact."
  The BBC's World News TV channel goes temporarily to black in China whenever the story about Mr Xi's visit is mentioned.
  Probably not.
target: The Queen has described Chinese officials as having been "very rude" during last October's state visit to the UK by President Xi Jinping.