A lock retainer for facilitating the secured connection of an adjacent pair of wall frame elements to one another by way of a lock cassette having an actuatable grip portion is disclosed. The lock retainer may comprise a flange portion disposed between a proximal portion and distal portion. A cassette compartment may retainingly engage a portion of the lock cassette with the grip portion remaining outward the lock retainer. The proximal portion is configured to be mounted in a retainer mounting aperture in a frame segment of a wall frame element. The lock retainer may include a retainer detent moveable between a securing and releasing positions. The detent may be resiliently biased toward the securing position. The detent may be on a detent lever having a release actuation portion enabling a user to manually overcome the resilient bias. Also disclosed is a modular wall frame system incorporating the lock retainer.