[General] sit on the lid

[vil]

Dear teachers,

Would you be kind enough to give me your considered opinion concerning the interpretation of the expression in bold in the following sentence?
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[FONT=&quot]I’ve kept it out of the newspapers so far. I can’t sit on the lid much longer. We’re too well known socially and otherwise. (E. S. Gardner, “The Case of the Lazy Lover”)[/FONT]
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[FONT=&quot]sit on the lid = muffle, keep down, keep silent, suppress[/FONT]
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[FONT=&quot]V.[/FONT]

 

[Tdol]

I suppose it's an extension on keep a lid on something.