Re: Professional genealogist? (Russia to London migration in early 19th century)
Can you please give the specific info as much as you know, especially about the date/s the family moved? The events in Russia might give a clue as to the reasons for the move, such as the military campaigns for example.
The national archives have naturalisation records, which provide the name of the place of origin. However, it’s hard to advise with no specifics.
What is CMJ?