be a [Londoner etc.] through and through

be a [Londoner/patriot/politician etc.] through and through  also be [French/good/honest etc.] through and through

if someone is a Londoner etc. or is French etc. through and through, they behave in a way that is typical of such a person and that is the most important part of their character He always managed to say the right thing. He was a politician through and through. She never really settled in England. She was French through and through.

See know through and through

See also: and, through