Lock assembly including bolt hold back function

This invention relates to a lock assembly (1) including a housing (2) and a latch bolt (3) that is moveable between an extended and retracted position under the influence of a biasing means (7). A retainer means (29) is adjustable between a first position, second position and third position. The retainer means (29) prevents movement of the latch bolt (3) from the retracted position when in first position, and does not prevent movement of the latch bolt (3) from the retracted position when in a second or third position. The retainer means (29) achieves a function often referred to as a whole back function.