Conversation so far:
What was Thompson like as a person?
He was plainly dressed, quiet, and observant.
What else was noticeable about his appearance?
His figure was short and compact.
Did he have any other distinguishing features?
his black hair was worn long all round, and cut square.
Are there any other interesting aspects about this article?
His complexion was of the gardener's ruddy brown.
Did he wear a beard?
CANNOTANSWER.
How did he wear his clothes?
was plainly dressed.
What else was unique about his appearance?
by saying he greatly resembled Curran the Irish Orator...

Question: What was his most defining feature?
Self-contained rewrite: What was David Thompson's most defining feature?