I have been getting news alerts on this story for a few days, but I was waiting for one of the stories to actually run a picture of the portrait before I posted it. Thankfully the BBC finally came through! The portrait is a large version of a relatively well-known miniature of Thomas Wyatt the Younger, which you can see here.
From the BBC article:
A recently rediscovered painting by Hans Holbein is expected to fetch between
