The invention relates to a latch unit (10; 210) which includes a bolt (16; 116; 216; 316; 416), a housing (12; 212; 412) for the bolt, guide means (14) for the bolt in the housing, first resilient bias means (20; 120; 420) for the bolt in the housing, the first resilient bias means urging the bolt in a forwards direction towards a holding position in which an end part (22; 222) of the bolt is outside the housing, and retaining means (56, 60; 156, 160; 456, 460) for the bolt, the retaining means comprising a first part (56; 156; 456) and a second part (60; 160; 460), the retaining means having an active condition in which the first part is engaged with the second part whereby to retain the bolt against movement in the said forwards direction, characterised by a second resilient bias means (58; 458) to hold the first and second parts in the active condition. It is a particular feature of the invention the bolt has {i} a holding position in which it can engage a keeper, {ii} a non-holding position in which it is disengaged from the keeper, and {iii} a retained position in which it cannot engage the keeper and in which it is retained by the retaining means (56, 60; 156, 160; 456, 460), the non-holding position being between the holding and retained positions. There is also provided a method of operating a latch unit (10) according as herein defined.