to let slip

“And he might appear rough, but he was in fact so gentle as to be almost shy, and she found herself telling him that she was able to read, a little, forgetting momentarily that her mother and father had been adamant that she was not to let slip the admission until the marriage had been legally formalised.”

Locked Rooms

“He was plain Charlie Ratcliffe until then, but then he started to let slip his real name was Steyning-Ratcliffe — and that's also when he joined the Double R Society. ”

War Game