It's possible that:
* She is a private person: She may have chosen to keep her professional activities confidential.
* She is involved in other fields: Her career might be in a different field entirely, and she might be involved in film or television in an off-screen capacity.
* The name is misspelled: It's possible that the name is a typo and you're actually looking for someone else.
If you have any additional information about Marguerite Lofthouse or the context of your search, it could be helpful in finding information about her involvement in film or television.