“In the last row: We have either Vyacheslav Trubnikov (Soviet that fed the BS to Steele) or perhaps Louis Sussman U.S. Ambassador to the U.K.”
I’ve changed my guess to Richard Dearlove. The Travis McGee picture is a little grainy. The person next to Halper appears to have a bit more hair on the top of his head than Dearlove. That might be a processing issue. The glasses and face look like Dearlove.
There is a picture of Dearlove in this relevant article:
Could be. Not quite sure why that person was included, I can think of plenty of other who stand out as more recognizable, like Adam Schiff. 8>)