Your master should really have kept the book under lock and key.

She told me that he was kept under lock and key.

It will last up to three weeks, but less if not kept under lock and key.

She talked of nothing less than keeping me under lock and key in the future.

Course they do want to keep me under lock and key.

His written statements were kept under key, in special files.

Few things in the lab were kept under lock and key.

"The most responsible thing you can do it keep them under secure lock and key."

"We have to keep the building under lock and key now, even from our students."

We can even ask that the petition be kept under lock and key.