Tom Hanks and Emma Thompson will be in the capital for the last day of the BFI London Film Festival.
The pair will be on the red carpet for the screening of their film Saving Mr Banks, the story of how the movie Mary Poppins was made.
More top news
A lamp in the tower which houses Big Ben is to be switched off for the first time in more than 70 years.
Sir Bruce entertained audiences for more than seven decades.
Work in the tower will also pause over the bank holiday weekend.