Since I said --
I wonder if our resident Brexit supporters are going to explain Trump's ability to force Sir Kim Darroch to resign illustrates our sovereignty.

--- Nigel, Stanron and Iains have all posted on other topics. I assume I was right in thinking they might not want to discuss what this shows and suggests about our sovereignty when dealing the the US.

I didn't comment because it was a false premise. Trump didn't force Darroch to resign. That was his own decision.
However, the fact that Trump was no longer willing to deal with him after his comments were made known makes it unsurprising that Darroch chose to resign.
If any one person (apart from Darroch) was responsible for causing the resignation, I would suggest it was whoever decided to leak the earlier comments, or the newspaper which decided that they were worth publishing.