Laughton's performance should be studied by every acting student. He gives us a Charlie Staggers who is funny, resourceful, honest and pathetic and with a great capacity to love and do right by others. He is a simple and good man with a deep soul, and his audition in the theatre at the climax of the picture is both sad and uplifting.
Viven Leigh demonstrates a great talent and the characteristics that made her so successful the following year as Scarlett O'Hara in "Gone With the Wind." In this film she begins as a self righteous and petty thief and by the end she has grown to become a highly successful but humbled actress. Leigh carries this change superbly and makes it completely believable. By any measure it is a great performance.
"Sidewalks of London" is also very well written, directed and edited. I rank this as one of the best English language films of the 1930s.