What does the expression "tongues in their heads" mean within the context?

Question

Can't hide it from them, can you? The valet and the coachman have tongues in their heads.

Answer 1

.In this context, "tongues in their heads" implies that the valet and the coachman are not silent or discreet; they are likely to talk or share information. The expression suggests that these individuals are not easily kept in the dark about things and are prone to speaking out or revealing information.