The actress Linda Bennett plays Penny, the little girl. She is supposed to be 7, going on 8.
There's very little info about her, looks like she only had 10 roles as a child.
But the bio in IMDB lists her as:Born: June 19, 1942
With the movie being filmed in 1954 or 55, she can't be 13.
You're right. She looks 7-8.
share[deleted]
According to IMDB the filimg dates were 28 October to 5 November 1954, only 8 day si all.
https://www.imdb.com/title/tt0047960/locations?ref_=ttrel_sa_4
The IMDB page on LInda bennett now ways she was born 12 December 1946 making her almost 8 when her scenes will filmed.
https://www.imdb.com/name/nm0071890/?ref_=tt_cl_t_6
So it now says she was born four and a half years later than it used to saay. Probably someone made a correction.