A lock mechanism to lock two parts relative to each other. The lock mechanism comprises a base plate (30) attachable a to one said parts with a pivot pin (26) connected thereto, a keep (38) being defined in the pivot pin. A lock body (24) is also provided and this defines a channel (33) within which the pivot pin locates for rotation of the lock body relative to the pivot pin. A locking arrangement (36) is located within the lock body, and includes a movable bolt (37), which in extended and retracted positions engages with or disengages from the keep (38) to prevent or allow rotation of the lock body relative to the pivot pin. A latch plate (40) may be provided on the other part to cooperate with the lock body. This allows a wide variety of different parts to be secured relative to each other.