I've had a look on Autodata - you've got two fuse boxes. One in the engine bay and one above the pedals behind the kick panel.
Autodata is not very helpful here either - as I can't see a fuse listed with the description "central locking"
Now looking at the fuse layout of the Rover 400 - it does have a fuse listed as "central locking/alarm"
The Rover 216 has fuse listed as "alarm" - now it is only a guess but this fuse may also be related to central locking. It is fuse F1 within the fuse box in the engine bay.
I'm not convinced yet that it is a blown fuse.
Have you tried your key on the passenger door to see if there is any central locking motor noise?
It could be a faulty solenoid motor on the drivers door.
The central locking is controled by a central locking control module, a black box - located to the right of the kick panel - drivers side - near pedals.
I wouldn't rush to replace this box yourself because it is linked to the imobiliser system and if replaced needs to be programmed/paired to the ECU. - time to consult autospark. (easier to live without central locking than have a car completely imobilised)
Depending how handy you are with all things electrical - you could remove the driver's door panel - and check if the solenoid is receiving power - and/or if activates when power is applied - power probe is the best tool for this.
hope this info helps