I know there are folks here who are good with Chaplin. I'm aware his signature varied a bit over the years. Also that wife Oona signed for him in later years.
How does this look from 1964 on the U.K. edition of Chaplin's MY AUTOBIOGRAPHY?
Definitely late 60’s as indicated on the letter. His signatures were all over the place at that time, the definitive “p” in Chaplin is prevalent still.