Central locking on rover 416 will lock passenger and the rear two back doors but will not lock or unlock drivers door

Sorry Andrew , no BCM on this vehicle . The Central Security Module is incharge of power door locks . Central Security Module For additional information, refer to Section 419-10 .
The central security module is equipped with a battery back-up which holds the programmed transmitter(s) memory in the event of the vehicle battery disconnection.
Principles of Operations The Door Switch Lock Function When a door lock switch is moved into the lock position or a door lock cylinder is rotated to the lock position, the door lock switch grounds the lock circuit input to the central security module. The central security module then provides 12 volts to one side of the door lock actuators contained in the door latch unit and simultaneously grounds the other side of the door lock actuators. This completes the door lock actuator circuit, causing the door lock actuators to rotate a cam assembly, which then locks the doors.

The Door Switch Unlock Function When a door lock switch is moved into the unlock position, the door lock switch grounds the unlock circuit input to the central security module. The central security module then provides 12 volts to the opposite side (relative to locking the door) of the door lock actuator(s) contained in the door latch unit and simultaneously grounds the other side of the door lock actuator(s). This completes the door lock actuator circuit, causing the door lock actuator(s) to rotate a cam assembly in the opposite direction, which then unlocks the door(s). The 12 volts which the central security module provides to the door lock actuator(s) are provided to each door lock actuator from the individual pins on the central security module connector.

Keyless Entry When a remote transmitter button is depressed, it transmits the appropriate command to the central security module as a radio frequency. The central security module receives the command from the remote transmitter through an antenna, which is incorporated in the central security module.
When the central security module receives a command from the remote transmitter, it then sends the appropriate output to control the desired devices. These outputs devices include:

• The front and rear door lock units.
• Central timer module (CTM).
• The liftgate release motor.
• The right and left side turn signal lamp(s).

The central security module sends a signal to the CTM when courtesy lamp illumination is required.
Computer Operated Locks Each front door lock actuator contains a bipolar motor that controls the lock and unlock linkage. The lock/unlock lever of both front door interior handles use linkage to actuate the lever lock switch located inside each front door lock actuator. Each lever lock switch remains in the unlock position until lock/unlock lever of the interior door handle is moved to the lock position. This action toggles the lever lock switch to the lock position. The central security module uses only one electrical input for both lever lock switches. The central security module cannot determine whether the driver or passenger door lever lock switch was actuated. Therefore, actuating the lock feature from either front door will have the same affect of locking all doors. Actuating the unlock feature will not unlock any other door.
The door lock control switches for both front doors also use only one input to the central security module.
Both rear passenger doors contain a rear door lock actuator that controls only electric lock or unlock of the door. Actuating the lock/unlock lever at either rear passenger door will have no effect on other doors.
The panic feature of the remote transmitter sounds the vehicle horn when the vehicle is not equipped with anti-theft. If the vehicle is equipped with anti-theft feature, a separate horn is sounds for the panic feature.

Change/repair the central locking motor inside the door.

Many rear doors have a child safety lever to keep the rear doors from unlocking. This lever will be located on the rear edge of the door and you can switch it to unlock those doors with the others. If you have the owner's manual it will give you directions, if not check with a dealer as they can tell you the procedure.

turn key twice when opening, ie turn right. once drivers door will unlock, turn twice passengers doors will unlock, and locking is turn anti clock wise once will lock all doors, turn twice will set door dead locks.dead locks will stop openand lock internal button working and handle from opening door. the same actions can be applied to the remote one press drivers door, two press passenger doors, press and hold unlock button for 5 seconds and rear window will open.

No, likely to be caused by the actuators in the lock mechanism failing usually causing the door to remain locked. The boor door can also fail this way, as do the front side doors. Replacement requires the whole lock unit to be replaced at a cost of roughly £60 a lock, and a hours work. Helps if you have small hands. Requires a full strip down of the door and you will need the lock unit, trim clips (a few quid) and a trim removal tool (tenner). You can bodge with a flat head screwdriver, but the tool does help prevent damage to the clips & trim panel.

sequence for freelander lock unlock, to lock 1press = door lock , 2press = door dead lock , to unlock 1 press = driver door unlock, 2 press = passenger doors unlock, also rear window can be operated from fob to do so press and hold unlock button for 3 or more seconds and rear window will roll down.neat feature.hope this helps

sequence for freelander lock unlock, to lock 1press = door lock , 2press = door dead lock , to unlock 1 press = driver door unlock, 2 press = passenger doors unlock, also rear window can be operated from fob to do so press and hold unlock button for 3 or more seconds and rear window will roll down.neat feature.hope this helps

Could be a relay for that door..
Or it could be the auto lock motor for that door.

Does it open from the outside once you have manually opened it from the inside.

Check your remote batteries.Listen for any sounds coming from the passenger door lock when operating the drivers door switch.The lock could be faulty.Have a diagnostic check done at a dealer to tell you whats wrong , this is normally free , before stripping anything..